It’s a bugfix and security release. So if you have an older version is highly recommended to patch and upgrade your wordpress powered blog.

Version 2.1.1 includes about 30 bug fixes, mostly minor things around encoding, XML-RPC, the object cache, and HTML code. It’s available for immediate download on our download page.

This is a low-to-medium priority update recommended for all WordPress users. Go here for more info about the new release.