If you mean just appear as app like Flickr in the Photo hub, then I guess it could be possible, though nothing points to that being available to devs at all. If you mean act like WLM in Messaging, then no that has to be done by Microsoft.
While Microsoft has no problem in releasing applications for Android, Google seem to behave like a little jealous kid. I don't think we'll ever see Google Talk integrated in the messaging hub.