He's had a hand in the writing, the story, or the teleplay for a lot of good episodes.
Several more are listed here http://www.imdb.com/name/nm0788167/filmoseries#tt0247082.
I think he's added some creativity to the show over the years and he's been a developer of the lab rats' episodes. This year he did Working Stiffs and A Space Oddity, and the upcoming Field Mice. It sounds like he is going off to develop other projects for CBS. I wish him luck!
working stiffs didn't like that one, a space oddity it was humerous but it's not my favorite, field mice is probabaly the last one he did on csi, hope it is good
him leaving could be good, or bad cause he has done several episodes i liked, but they can bring in some new writers and give the show new blood