Async.cls

/* 
 * Author: Kevin O'Hara
 * Date: 02/10/2012
 * 
 * Description: The Async class aims to circumvent a limitation of asynchronous (@future)
 * methods in Salesforce. The current @future implementation will only allow for primitives
 * or collections of primitives to be passed into an @future method. The Async class uses
 * native JSON serialization/deserialization to allow for passing an SObject, or List<SObject>
 * into an asynchronous method for DML operations. A helper method is also included for making 
 * the serialization processes simpler.
 */

public class Async {

    /***********************/
    /* ASYNC DML METHODS   */
    /***********************/
    
    // insert sobjects
    @future
    public static void insertSObjects(String jsonString) {
        
        List<SObject> sObjs = new List<SObject>();
        
        try {
            sObjs = (List<SObject>) JSON.deserialize(jsonString, List<SObject>.class);
        } catch (Exception e) {
            System.debug('Error in JSON deserialization');
        }
        
        if(!sObjs.isEmpty()) {
            try {
                insert sObjs;
            } catch (Exception e) {
                System.debug('Error inserting SObjects');
            }
            
        } 
        
    }
    
    // upsert sobjects
    @future
    public static void upsertSObjects(String jsonString) {
        
        List<SObject> sObjs = new List<SObject>();
        
        try {
            sObjs = (List<SObject>) JSON.deserialize(jsonString, List<SObject>.class);
        } catch (Exception e) {
            System.debug('Error in JSON deserialization');
        }
        
        if(!sObjs.isEmpty()) {
            try {
                upsert sObjs;
            } catch (Exception e) {
                System.debug('Error upserting SObjects');
            }
            
        } 
        
    }
    
    // update sobjects
    @future
    public static void updateSObjects(String jsonString) {
        
        List<SObject> sObjs = new List<SObject>();
        
        try {
            sObjs = (List<SObject>) JSON.deserialize(jsonString, List<SObject>.class);
        } catch (Exception e) {
            System.debug('Error in JSON deserialization');
        }
        
        if(!sObjs.isEmpty()) {
            try {
                update sObjs;
            } catch (Exception e) {
                System.debug('Error updating SObjects');
            }
            
        } 
        
    }
    
    // delete sobjects
    @future
    public static void deleteSObjects(String jsonString) {
        
        List<SObject> sObjs = new List<SObject>();
        
        try {
            sObjs = (List<SObject>) JSON.deserialize(jsonString, List<SObject>.class);
        } catch (Exception e) {
            System.debug('Error in JSON deserialization');
        }
        
        if(!sObjs.isEmpty()) {
            try {
                delete sObjs;
            } catch (Exception e) {
                System.debug('Error deleting SObjects');
            }
            
        } 
        
    }
    
    /***********************/
    /* HELPER METHODS      */
    /***********************/
    
    // list of sobjects
    public static String prepare(List<SObject> sObjs) {
        
        try {
            return JSON.serialize(sObjs);
        } catch (Exception e) {
            System.debug('Error in SObject List serialization');
        }
        
    }
    
    // single sobject
    public static String prepare(SObject sObj) {
        
        try {
            return JSON.serialize(new List<SObject>{sObj});
        } catch (Exception e) {
            System.debug('Error in SObject serialization');
        }
        
    }
    
}

Async_Test.cls

@isTest
private class Async_Test {
  
  static List<Lead> leads;
  
  static {
    
    leads = new List<Lead>();
      
      Lead l1 = new Lead();
      l1.FirstName = 'Test1';
      l1.LastName = 'TestLast1';
      l1.Email = '[email protected]';
      l1.Status = 'New';
      l1.Company = 'Test Co';
      leads.add(l1);
      
      Lead l2 = new Lead();
      l2.FirstName = 'Test2';
      l2.LastName = 'TestLast2';
      l2.Email = '[email protected]';
      l2.Status = 'New';
      l2.Company = 'Test Co';
      leads.add(l2);
      
  }
  

    static testMethod void testInsertList() {
      Async.insertSObjects(Async.prepare(leads));
    }
    
     static testMethod void testInsertSingle() {  
      Async.insertSObjects(Async.prepare(leads.get(0)));
    }
    
     static testMethod void testUpdateList() {
      insert leads;
      for(Lead l : leads) {
        l.FirstName = 'NewName';
      }
      Async.updateSObjects(Async.prepare(leads));
    }
    
    static testMethod void testUpdateSingle() {
      insert leads;
      leads.get(0).FirstName = 'NewName';
      Async.updateSObjects(Async.prepare(leads.get(0)));
    }
    
    static testMethod void testUpsertList() {
      insert leads;
      for(Lead l : leads) {
        l.FirstName = 'NewName';
      }
      Async.upsertSObjects(Async.prepare(leads));  
    }
    
    static testMethod void testUpsertSingle() {
      insert leads;
      leads.get(0).FirstName = 'NewName';
      Async.upsertSObjects(Async.prepare(leads.get(0)));
    }
    
    static testMethod void testDeleteList() {
      insert leads;
      for(Lead l : leads) {
        l.FirstName = 'NewName';
      }
      Async.deleteSObjects(Async.prepare(leads));
    }
    
    static testMethod void testDeleteSingle() {
      insert leads;
      leads.get(0).FirstName = 'NewName';
      Async.deleteSObjects(Async.prepare(leads.get(0)));
    }
    
    static testMethod void forceSingleInsertFailure() {
      SObject s;  
      Async.insertSObjects(Async.prepare(s));
    }
    
    static testMethod void forceListInsertFailure() {
      List<SObject> s = new List<SObject>();  
      Async.insertSObjects(Async.prepare(s));
    }
    
    static testMethod void forceSingleUpdateFailure() {
      SObject s;  
      Async.updateSObjects(Async.prepare(s));
    }
    
    static testMethod void forceListUpdateFailure() {
      List<SObject> s = new List<SObject>();  
      Async.updateSObjects(Async.prepare(s));
    }
    
    static testMethod void forceSingleUpsertFailure() {
      SObject s;  
      Async.upsertSObjects(Async.prepare(s));
    }
    
    static testMethod void forceListUpsertFailure() {
      List<SObject> s = new List<SObject>();  
      Async.upsertSObjects(Async.prepare(s));
    }
    
    static testMethod void forceSingleDeleteFailure() {
      SObject s;  
      Async.deleteSObjects(Async.prepare(s));
    }
    
    static testMethod void forceListDeleteFailure() {
      List<SObject> s = new List<SObject>();  
      Async.deleteSObjects(Async.prepare(s));
    }
    
}

Usage

// EXAMPLE

// 1. Query some leads
List<Lead> lds = [SELECT Id, FirstName, LastName FROM Lead LIMIT 2];

// 2. Make some changes
for(Lead l : lds) {
    l.FirstName = 'BLAHHH';
}

// 3. Use the prepare() helper method to serialize to JSON, then call the appropriate DML function
Async.updateSObjects(Async.prepare(lds));

// RESULT: Your DML is offloaded to an async request