Think about it, if you were to stretch that screen on the handset when and only if, plugged into the TV set, it would look hacky and awful at worst!
- Would chew up a lot of memory to allow translation on the fly to accomodate the width of Android's graphics frame-buffer device - which is a limited size based on the resolution of the handset and only one framebuffer is available!
- An extra layer of complexity to tell Android "Right, we're plugged into TV, now stretch"
- As RAM is chewed up to "accomodate" a bigger buffer to hold the graphics in a stretched state for desktop screen/TV, that could result in Android slowing down to a crawl as the apps would not have enough RAM available to run in.
All in all, it may be do-able, but having to reserve memory for the "stretched" resolution, say, for example, 800x480 resolution, Portrait mode on WVGA, 480x800, Landscape mode, 800x480, using that one singular frame-buffer device.
Have a mosey around in the kernel configuration as there may be something in there for Media/TV capture...? as for the actual app within Android itself, have not seen it. Worthy a investigation into the kernel though :)
But then again, if there's a chip that supports HDMI, maybe its a different story, but interesting question OP! +1 from me!