Unexpected, but not without precedent. XNA on Xbox/Windows Phone 7/Windows, Unity3D across its range of supported platforms; it'll be interesting to see with Sony come up with.
What is surprising is that Sony has taken a Microsoft invention and said "We'll be using that too". Not, "We've created something brilliant (and oh, yeah, it looks just like this thing from Microsoft)", or "We're using Java", or "Dalvik" (since Playstation Suite taps Android devices too).