IGN reports that Darkstalkers anime hit stores in the form of UMD today. This was announced earlier but then dropped off the radar and just kind of popped up. The two episodes are Night Warriors Darkstalkers Revenge Alpha and Night Warriors Darkstalkers Revenge Omega and retail for $19.99 each.
It was also previously announced that the Street Fighter anime Street Fighter II V (The series), and Street Fighter Alpha: The Movie would be coming to UMD but so far nothing else has been heard of that. They were slated for Q2 2006 release dates so there is a good chance they are still on the way.
I have not seen the Dark Stalkers anime although I have seen all of the Street Fighter ones. I personally think that Street Fighter II: The Animated Movie was the best of them, but it isn’t on the list.