Here's whatsnew per the homepage:
New for 2.0:
As of 4:59 EST today, Visual PinMAME is completely open source!
Since the last of Stern's Whitestar games turned 3 years old today, we are able to release the full source code to the public.
At the same time, the expiry date was effectively removed, so there you have it, cabinet builders. :)
Not a whole lot of new features I'm afraid, but it's all in the whatsnew.txt anyway.
Get it here: