Krazygluon: Love the name!
fzymnr: You likely have a block or item ID conflict. Since this is such a frequent problem I think I'm just going to add custom error-handling in the next release (I wish Mojang had made Minecraft's error reports more accessible to the user, but...) and automatically pick a free block or item ID if a conflict is detected. Until then, run Minecraft from the command line to figure out what ID is conflicting and change the config file.
Sleeeper: I haven't taken Buildcraft pipes into account yet, but the full release will include greater Buildcraft compatibility (fusion reactors will distribute fuel between slots, etc.).
ttradno: The laser rangefinder (since v.65) might be the solution you're looking for. Left-click a missile while holding one and it will input the rangefinder's last coordinates.
MagusUnion: Sure, I'm helping out with a new antenna my adviser developed to pick up electron Bernstein waves from fusion plasmas. Assuming we can get the damn thing to work, it's going into the DIII-D tokamak next year. (And don't say you're "only" a geologist, all areas of science are worthy of study)
Tremelay: If you're getting an ArrayIndexOutOfBoundsException, you (or ID Resolver) have set an ID number higher than the size of Minecraft's ID array. Setting the warhead block to ID 30258 is definitely your issue, since Minecraft can only handle 256 blocks (items are a different story).
General news: Since I'm not going to get multiplayer support done before the conference, I figure that including reusable passenger rockets (replace the chemical-fueled booster with a rechargeable ion drive, HAYO!) and a mobile auto-miner in this weekend's update should be a decent consolation prize. You're going to love the autominer - it'll mine down to bedrock, pull its pipe up, move over nine squares, and repeat until the Lapotrons run out.