I'm hoping that one day, Minecraft gets completely open source and is ported away from Java. I've tried and failed to write a plugin for Bukkit and the whole ecosystem is horrible. When your modding toolkit involves importing craptons of JARs and decompiling the rest, something's really wrong.
If it wasn't written in Java it would be even harder to mod, with them not officially supporting it. The only reason it's working so well now is because Java can be decompiled rather easily.