I have a friend who has always been a fan of SubEthaEdit, I like the idea but not the implementation. Is there a similar plugin available for emacs? Normally

I have a friend who has always been a fan of SubEthaEdit, I like the idea but not the implementation. Is there a similar plugin available for emacs? Normally when I'm actively editting code that two people are sharing remotely, we just commit/update a lot. It tends to run up the revision numbers, but I can't think of a better way. Any ideas?