I've got a feature request, but the implementation will be a bit involved. Should be an interesting problem to solve if you're interested, though. What I'm looking for is the ability to use an ACTION_SEND intent like that used by the Gallery app for sharing and have it send it to a GoogleTV device. The best I can figure it, UPnP/DLNA is the best chance for getting this to work, so your app has already done most of the hard part already.
The remaining work would be to pair the devices (this step is well documented, and the GoogleTV Remote app is open source), send a custom URI from the sending device to the GoogleTV device (using their IP-to-IP protocol, again fairly well documented), translating that URI into a file on the sending device (this part will be the tricky bit, I think, and depends on how your code is structured), and playing the media via UPnP/DLNA (which you've already done).
I'd love to help in any way possible should you decide to take this on. I've done a decent amount of development both on my own and professionally. I've also briefly familiarized with the GoogleTV protocols involved (just at a high level, but they're fairly straightforward). The main reason I don't do this myself is because most of the work is in creating the UPnP/DLNA portion. It seems silly to duplicate efforts here.
The remaining work would be to pair the devices (this step is well documented, and the GoogleTV Remote app is open source), send a custom URI from the sending device to the GoogleTV device (using their IP-to-IP protocol, again fairly well documented), translating that URI into a file on the sending device (this part will be the tricky bit, I think, and depends on how your code is structured), and playing the media via UPnP/DLNA (which you've already done).
I'd love to help in any way possible should you decide to take this on. I've done a decent amount of development both on my own and professionally. I've also briefly familiarized with the GoogleTV protocols involved (just at a high level, but they're fairly straightforward). The main reason I don't do this myself is because most of the work is in creating the UPnP/DLNA portion. It seems silly to duplicate efforts here.