I feel potentially hit by the iron edges of the GPL, right now . Whatever Bukkit is or can be, at some point the plugin API will come and there are a couple of questions to be answered on how and what with other mods. There is no doubt that using Bukkit as official API doesn't make any sense, so a Mojang-made plugin API has to come and some of the question have to be answered on the way there. Obviously Mojang is working towards integrating modding better, if you keep checking changes and reading the change lists at Mojang.com. I can't judge how far they are with a Plugin API and how far that will be at the time of release, of course. Who would've guessed that even after the initial discussions about GPL/LGPL back then, that they a GPL-kill-switch-bombs in a project like this, "for the good in the community" - of course this can only be speculation, as we can't be sure what's the case under which countries law and how much it actually affects stuff, and if it applies at all. Whose and which actions have done how much damage to the Bukkit community and the whole Minecraft community .... remains to be judged afterwards. If/once it's there it will be documented "somewhere", you can be sure that the API will not be obfuscated.