If you had happened to of updated Minecraft to version 1.1, please save a copy of all the minecraft.jar files that you have currently so that you can still play on Multiplayer until the server is ready to update to 1.1.
Also,
I do ask that NO ONE post the 1.0.1 jar file on opticraft. It is against the ToS (Terms of Service) of Minecraft and can be responded by Mojang with legal action.