Unfortunately, the server has to wait a while for the latest Bukkit release. This means that the server will stay on 1.2.5 for awhile before moving to Bukkit. If we are lucky, this transition should be pretty smooth. If we are not, some plugins may break and some functionality may be lost.
If you want to play on the server but have 1.3, you can learn how to downgrade here: http://www.minecraftmine.org/how-to-downgrade-minecraft/
Happy mining!
~MDCreator