As I mentioned in a previous post. Snake taxonomy has recently been completely revamped based on research on the evolution of snake venom. Zimmer has an interesting post on the subject. The Panda's Thumb has a post as well. Note comments 60039, 60220, and 60221. Note also the very diplomatic, but total, slapdown of those comments in 60050, 60089, and 60247. Classic! The moral of the exchange is that one should do ones research before trying to criticize.
There is also a thread on the same subject here. One intersting note concerning fossil snakes. This and this provide some interesting info on snake evolution.