WordPress 2.1 has be updated to 2.1.1
The update is a low to medium priority update and:
includes about 30 bug fixes, mostly minor things around encoding, XML-RPC, the object cache, and HTML code.
This is a list of the files changed from 2.1 to 2.1.1:
It would be irresponsible of me to recommend that you simply update those files. Instead I’ll recommend that you read the upgrade instructions.