The BBC reported on the world's smallest snake.
Going by the name of Leptotyphlops carlae this pint sized snake was discovered on Barbados. It's about 10cm long, and females lay one egg with the hatchling being born with about half it's adult body weight.
They eat termites which really would explain their size, as each termite consumed would give more energy for the snake to use.
According to physorg.com there should be more information on this snake being published sometime today (I suspect closer to the end of the day over here) which should be an interesting read.
From the news reports they are saying that this is probably as small as you can get with regards to snakes. It probably becomes less viable from an evolutionary standpoint for a snake to get any smaller.
I'm still going to speculate here but I guess that has more to do with egg size then anything else. It probably is that if the snake was any smaller it would not be viable to reproduce because the young would be born with more of it's adult body weight until you get to a point where the mother is basically giving birth to an adult snake.
That would be too much of a strain on the adult and the population would be even more difficult to maintain then it already is.
I guess we'll just have to see with regards to what the discoverers think of this snake.