If you're using the new Minecraft launcher, you have a choice on whether or not you want to update to the latest Minecraft release - simply choose "Not now" when it asks if you want to update and you can continue to play on your pre-update Minecraft server.
If you're not using the new Minecraft launcher, backup your old launcher and update it by downloading it from http://minecraft.net, then follow the steps above.
It usually takes us a few hours AT LEAST to get Bukkit working with the latest Minecraft update, so you're better off playing a different game or staying on the previous version of Minecraft, instead. If you have a special server that requires lots of mods, like a class-based server, consider backing up your world, running the new Minecraft update and calling it a grief/fun/fool-around period OR stay on your current version and just keep playing.
Just remember, always backup so you can switch between versions. You're no longer...
We'll be having some scheduled maintenance tonight in a few hours. The forums will be locked down and moved to a new server. We'll provide you with the IP you can add to your hosts file to switch over to the new server immediately.
See you on the new server.
EDIT: Postponed until tomorrow. The downtime should be very short and mostly depend on how long it takes for you to see the new server.
Server maintenance COMPLETED with little to no issues. Thanks for your patience and cooperation!
Due to factors beyond our control, Leaky - our bug tracker - will be down for a while until we work something out to get it back up. The server that is hosting Leaky is going offline with short notice.
Sorry for any inconvenience this may cause, we're making backups and will be restoring them on a new server as soon as we possibly can.