The ZuneHD has been released in America. As it directly supports XNA there's a reasonably good chance XAGE will eventually target this. Portable XAGE gaming would be a terrific novelty, for me if no-one else.
That said, what is an even more tantalising prospect is that of iPhone support, due to the large, affluent user base and the recent success of the Monkey Island re-release. However, given XAGE is built using C#/XNA and iPhone uses Objective-C, there was never any real hope of the iPhone being supported.
Until now. The open-source XnaTouch project aims to help port Zune (XNA) games to the iPhone. They have a short video up showing an XNA game running on the iPhone simulator here. Of course, this is all miles away at the moment and would require an investment of several thousand pounds of new hardware, but it's yet another potential direction for the engine. I'll have to keep a close eye on XnaTouch to see just how feasible it is, but potentially there's the possibility of some ridiculously convoluted porting fun, e.g:
AGS game -> XAGE -> Publish to ZuneHD -> Port to iPhone (via Mac)
In the meantime I really ought to get the GUI customisation finished. Finally releasing The Fourth Wall to XBLIG will be a tremendous relief - conclusive proof that XAGE is not vapourware.