I build Blender myself, and had the same issues when exporting from the latest builds of Blender. To get collada export to work for SL again, I had to download and export using one of the 2.58 versions available on Graphicall.org. This only applies to rigged meshes. Non-rigged meshes exports fine, and imports fine to SL, from any 2.59 version of Blender.