Wait for UDK 4 for and we will only have kismet and C++ code they have gotten rid of UnrealScript , also dynamic C++ compiling on the fly. See last 2 minutes of video.
There are so many things wrong with this post that it isn't even funny. UnrealScript has been around since Unreal Engine 1 and is still in UE 4. Dynamic compilation is very real as you see in the video, yet that is UnrealScript being shown. Yes you can probably indirectly
dynamically compile C++ files that are bound
to UnrealScript classes, but that does not include dynamically compiling core engine code as I'm sure that would not be possible with the editor in use (the engine and editor use the same executable so make up your own minds...).
Please don't post misinformation about Unreal Engine on this site as most people don't seem too knowledgeable in what it can do and it really is a great tool to utilize for rapid development of pretty much any kind of game.