A new version of Blender was released a couple of weeks ago. It has 180 fixes that will be helpful. There are some new features but those are not for anything we do in Second Life. Also, Gaia Clary has a Collada fix rigged mesh over on Machinimatrix.org.
Simple Blender Install
To have multiple versions of Blender installed download and use the Blender Zip Archive. The zip file contains a working copy of Blender in a folder. The folder can be placed anywhere in your file system and work. One unzips the file to a folder, opens the folder, navigates to the blender.exe file, right click and drag it to the desktop or Launch Bar, release, and select Create Shortcut. That’s it. You have an independent install of Blender.
This install style makes it easy to switch between working versions of Blender.
The list of Blender shortcut keys is long. There is a nice list of Blender 2.5 shortcut keys here. As best I can tell the keys are the same in 2.5x and 2.6x.