There are some interesting things happening in Android gaming, and more specifically, in G1 Gaming. Take for instance the new Zeboo console designed as an affordable alternative to emerging markets. Turns out that the units are hacked G1s!
And check out the first video below (found via Android Central) that demonstrates the alpha GP2X game emulator for Android. It can load games originally designed to run on MAME, SNES, Sega Genesis, Game Gear and other consoles. Wow.
I had a decent experience running NesEmu on my G1, But Nesoid is definitely better. It is $1.99 in the Android Market. Thanks to @androidrights for pointing this one out to me. I made a quick video to demonstrate: