SVN?! Gross! You know, there is a rule on here about flaming other people.
And yeah, that's a bit of a pet project that I decided to start working on. Ever since food and classic mode were introduced it kind of annoyed me that peaceful mode is still so watered down, so my idea is to turn it into a mode where you live off of the land, while simultaneously making the standard difficulty settings a bit tougher.
I'm pretty impressed with how easy the Minecraft code is to modify and expand upon. I've never really worked with Java before, so I've found that to be more of a roadblock than deciphering Notch/Jeb's code (and it's really not hard to adjust to Java if you know C++ and/or C#).