While any official mod support is a good thing, I worry about the robustness of Bukkit as compared to MCF, and, of course, the delay in a 1.4 update.
Would this be comparable to when Apple moved from PowerPC to Intel? Everything needs to be rewritten, and many mods will get left in the dust if their authors don't feel like learning a new API?
I will retain cautious optimism. I have complete confidence in the IC2 team, at least, although I would love to hear more coder's opinions on the issue.
Edit: Would the Bukkit Team really be able prevent the Forge Team from modding some class files to supplement Bukkit, now that they're an official part of Minecraft? I mean, I could understand if download Bukkit and Forge seperately and try to mash them together, but if Bukkit comes standard on the Jar, meaning everyone has it, how is it different from putting Forge on a stock Minecraft.jar now?
Editception: Edited my edit for clarification.