Just completed a Salesforce -> Netsuite POST using Salesforce Apex Classes & Triggers along with an active NetSuite RESTlet.  Not a complete integration at all (Informatica Cloud is pretty easy!) but it might be helpful for some.  Since I've edited the parameters, field names, etc. in my implemenation, I figured I'd at least write up the resources online to help folks start out.  This does a one-way push of data from SFDC to Netsuite, and I make that happen on a trigger (basically to add a client to our Netsuite client list):

Netsuite RESTlet (POST Method from their helpcenter)

// Create a standard NetSuite record
function createRecord(datain)
{
    var err = new Object();
   
    // Validate if mandatory record type is set in the request
    if (!datain.recordtype)
    {
        err.status = "failed";
        err.message= "missing recordtype";
        return err;
    }
   
    var record = nlapiCreateRecord(datain.recordtype);
   
    for (var fieldname in datain)
    {
     if (datain.hasOwnProperty(fieldname))
     {
         if (fieldname != 'recordtype' && fieldname != 'id')
         {
             var value = datain[fieldname];
             if (value && typeof value != 'object') // ignore other type of parameters
             {
                 record.setFieldValue(fieldname, value);
             }
         }
     }
    }
    var recordId = nlapiSubmitRecord(record);
    nlapiLogExecution('DEBUG','id='+recordId);
   
    var nlobj = nlapiLoadRecord(datain.recordtype,recordId);
    return nlobj;
}

Deploy that script using the POST Function "createRecord" and find the external URL of the script deployment (something like ...netsuite.com/app/site/hosting/restlet.nl?script=##&deploy=#

Then I used this site as the outline for the APEX:  http://docs.servicerocket.com/display/SFJIRA/Writing+Apex+Class+to+call+for+Connector+RESTful+webservice

just modify the JSON to be appropriate for your entry, and modify the headers, since Netsuite doesn't use a basic/blob like that I don't think.

global class NetsuiteWebserviceCallout {
    @future (callout=true)
    WebService static void createRecord ( String recordType, String entityid, String externalid, String companyname ) {
 
        //Construct HTTP request and response
        HttpRequest req = new HttpRequest();
        HttpResponse res = new HttpResponse();
        Http http = new Http();
        String responseBody;
        
        //Construct Authorization and Content header
        String authorizationHeader = 'NLAuth nlauth_account=[YOURACCOUNT#], nlauth_email=[YOUREMAIL], nlauth_signature=[YOURPASSWORD]';
        req.setHeader('Authorization', authorizationHeader);
        req.setHeader('Content-Type','application/json');
 
        //Construct Endpoint
        String endpoint = '[YOURENDPOINT from the Script Deployment]';
 
        //Set Method and Endpoint and Body
        req.setMethod('POST');
        req.setEndpoint(endpoint);

//you need the minimum field pattern for whatever entity you are posting, reference their API guide
        req.setBody('{"recordtype":"'+recordType+'", "entityid":"'+entityid+'", "externalid":"'+externalid+'", "companyname":"'+companyname+'"}');
 

//to pass the apex test
        if (!Test.isRunningTest()){
 
            try {
               //Send endpoint to Netsuite
               res = http.send(req);
               responseBody = res.getBody();
               } catch(System.CalloutException e) {System.debug(res.toString());
            }
        }
       

//else if test is running
        else {
        // dummy data
        responseBody = '200';
        }
  }
        
 
}

---------

trigger -- you'll notice I have a few custom fields -- external ID is an autonumber field, and NetSuiteRecordType is a text field with a default value of "customer" on this object, since that's the recordType netsuite is looking for in the JSON.

trigger CreateNetsuiteCustomer on CustomObject__c (after insert) {
      
          for (CustomObject__c c : Trigger.new) {
 
                    //Define parameters to be used in calling Apex Class
                   
                    String recordType = c.NetSuiterecordType__c;
                    String entityid = c.Name;
                    String externalid = c.externalid__c;
                    String companyname = c.Name;
                 
                  //Execute the trigger
               NetsuiteWebserviceCallout.createRecord (recordType ,entityid ,externalid ,companyname);
          }        
}