As far as I have seen it intel simply said "gallium is cool but we have been doing classic mesa and don't see much of a benefit of porting the code and learning that stuff etc. so we'll just keep doing what we were doing before".
If i965g gets mainlined again and gets close in features (e.g. only OpenGL 2.1 right now) and performance maybe the intel developers switch over.
Much activity lately, e.g. a very big merge from "origin/master" so I might even be outdated right now.