You may notice some of the newer animations in Second Life are getting better. There is motion capture to thank for some measure of improvement. Another contributor to the improvement is Avastar, a for purchase add-on to Blender.
One of the other handy features of Avastar is the ability to handle rigging a mesh. So, clothes makers and those making other objects rigged to the avatar will find Avastar a handy tool. I think this video gives one a good example of what it can do.