bukkit builds for new versions of MC tend to have crash bugs for the first few builds and generally takes about a day or so to get a stable version out.

MC v1.6.6(going to be deleted after the server gets updated to the new version.). One note though is that if you played on any of your sp worlds on 1.7, they might corrupt or crash if you try to load them in 1.6.6 so you shouldn't play on those SP worlds either when running on 1.6.6.

Rename the minecraft jar in your \Users\<username>\AppData\Roaming\.minecraft\bin (for vista and 7.) or \Documents and Settings\<username>\Aplication Data\.minecraft\bin (in xp) folder to minecraft_bk, Then download the attachment into that folder. If you want to play on 1.7 again you can either do a force update if your using the newer launcher, or delete the minecraft jar and rename the backup you made before to minecraft.

Going to wait a day or 2 for a stable build of bukkit that works with 1.7 you can dl and use 1.6.6 in the mean time.

updated to MC 1.7.2