Yes, we have been using PlayN for a few months right now, it is true that it is not as complete as other cross-platform tools, but it is starting to get a really good shape, someone just made a C-ish backend last month and got a working example on iOS, but this backend could help us with ports to WP7 and consoles.

It was originally shown off as ForPlay at Google I/O '11. Here is a video of the talk: http://www.youtube.com/watch?v=F_sbusEUz5w

I'm really glad they changed the framework name too =D