Rhindle has posted a guide on how to run shareware/homebrew on the 360:

Well sort of ...

I was messing around with the Media Extender interface on the X360, and noticed that the "More Programs" linked to a couple of apps installed on my PC as part of the Media Center Package, including MS Instant Messenger and some other stuff. All of these run when you access them from the 360 Media Extender client. The 360 essentially seems to act as a dumb terminal, interfacing with the application running on the PC.

Here's where things really get interesting: It's apparently very easy to integrate Windows applications into the MCE "More Programs" tab. All you have to do is build a link in a format specified by Microsoft and do some minor optimization, and the app will run in MCE. Here is how MS describes the process of building games for MCE: http://msdn.microsoft.com/library/d...vgameswinmc.asp

So I downloaded a couple of apps and installed them on MCE, switched over to the 360, and lo and behold, most of them run perfectly. I was able to run apps with modified browsers to pull down news stories, stock quotes, sports scores etc., as well as several Internet Radio clients.

I also tried installing a couple of shareware games, including a Tetris clone and some card games. Interestingly, they all launch on the 360, but crash soon afterwards. My guess is that you could get them to run with some optimization. There even is a MAME emu for MCE out there, though I haven't tried to install it.

My guess is that it will be difficult to get anything other than simple casual games to run in real time using the interface, due to lag in response times. But I would think getting something like a full web browser up and running should be achievable.