To get MapKit to compile correctly with 2.4, I had to do the following:
In MapKit.h
//#ifdef CORDOVA_FRAMEWORK
// #import <Cordova/CDVPlugin.h>
//#else
// #import "CDVPlugin.h"
//#endif
#import <Cordova/CDVPlugin.h>
In MapKit.m
//#ifdef CORDOVA_FRAMEWORK
// PhoneGap >= 1.2.0
// #import <Cordova/JSONKit.h>
//#else
// https://github.com/johnezang/JSONKit
// #import "JSONKit.h"
//#endif
#import <Cordova/CDVJSON.h>
Then in config.xml, add this to the plugin list.
<plugin name="MapKitView" value="MapKitView" />