Thunder, I ported version 4 to bukkit. I'm still testing it (I'd like to use that map you have for testing so I can quickly check everything) but for the features I have tested, it has worked perfectly.
I had to make very small changes to make it work with bukkit. So small that I hope that when you see how easy compiling it for bukkit is, you can compile it with your original source code and make a bukkit release a standard version. Essentially there were 4 changes : some tweaks to the order of instructions in your core mod file, changing net.minecraft.src to net.minecraft.server with find and replace, making references in your code explicit, and changes to NetworkAPI_Server because bukkit has slightly different names for things in 2 places.
The decompiler made a mess of your source code, and without comments, it was a stressful experience. While I have it working this time, I don't want to maintain a bukkit port unless I have access to the real source code and comments.
I'll have it released here and I'll give you an exact description of all the changes I had to make within 24 hours, assuming I don't find any huge bugs.