This is mainly a maintentance release, with some improvements to boot:

• Fixed bug where expiration time set by backend gets divided by 1000, leading to repeated requests from clients
• Better locking during initialization
• Reuse of MimeType? and SRS objects, better performance
• Improved error messages, thanks to Andrea and Mike
• Support for global vendor parameters to WMS backend, when using getCapabilities configuration

A fair bit of work has been done on Google Earth / KML support, we'll get back to this when an official release of GeoServer can support it.

Download it from SourceForge