Machinimatrix.org is releasing a new tool for use by Second Life™ creators. This one is called Sparkles Tool Box. The promotional video comes as a tutorial for merging UVMaps and shows people how to perform the task manually. Then goes on to show how much time can be saved by using the new tool.[youtube HBU6f-AIXdI]
If you already have AvaStar, you may not need the new tool, depending on your workflow. I have Blender 2.71 and avastar-1.1-beta-4_blender-2-70 installed. When I copy the AvaStar model’s lower, upper, and head and combine them I get the UVMap result that Sparkles provides as shown in the video.
But, if you are working with anything other than the AvaStar model, Sparkles is going to be a time saver.