I ran through and updated our Minecraft server last night to the latest build, 1.2.3. Everything appears to have transitioned well. Most plugins are still present and functioning as they were with exception of the SignLift and unfortunately the DeathChest ones. I'll look for a replacement if it seems the author isn't going to update it. I have yet to run a thorough test given my traveling but I hope to this weekend.
So far, I did see a funny bug where the new way Minecraft generates maps has changed since there are new biomes and such. This causes the edges of an existing explored map to suddenly change to the new style map. So where a desert existed might suddenly end into the sheer wall of a cut in half mountain. Some of our maps this may not be an issue, but it suggests that we could possibly look to start a new map to take full advantage of the new map system in a flawless way. This will be up for discussion.
Keep in mind, a client update is required to enter the server. You can get that here.
Thanks for playing.