Sure, but there are already a number of machines you can do that with. I'm sure there is some reason to do this, but I can't think of many good ones.

FWIW, Debian is probably even easier than Android (less specific hardware requirements.) However, AFAIK noone has developed a Linux kernel to run on Apple's A4 SoC, in either the iPad or AppleTV.

They would be a nifty cheap choice for a MythTV frontend (among other things), but AFAIK it would be quite significant development & reverse-engineering work for proper hardware support. As the other reply says, there are lots of similar options that run Linux (and presumably Android) right now.