Now that 1.5 has come out I feel that this is the best time to start programming core mods. Bukkit has done very well in providing me with good builds to use mods on. Unfortunately I need more than the every day programmer offers. I have multiple ideas for this server that require a higher programming than the ones offered on everyday Minecraft forums. (Thats not to say I won't deny you if you have made a well written or any mod at all). I need planes, new blocks, web-to-game synchronization, true map generators, and more. I want to take this game and make it the best it can be. Your benefits? There is good profit in the web my friend and its more than just giant towers //set to diamond. If you would like to talk to me about this leave a comment or email me at firstname.lastname@example.org (Yes this is a mailTo link so unless you run your email on your computer and not through a browser don't click this). I am currently programming an installer that adds and modifies any client-side files necessary in order for players to have what they need to play on my server. It should be done in a few days.
In the mean time bukkit announced that they are currently working on a build for 1.5 and it should be done within the day. I'll keep you posted.