Update: We have some gameplay video
We are attempting to use Spriter for our XNA game Captain Dubstep - http://www.captaindubstep.net/
I say attempting because it's still beta and we may have to drop it for this game. There is already a few times where I edited the XML files by hand to correct issues and there isn't great support for pixel art yet. So far though, it looks like we'll be able to use Spriter for most characters.