Well I don't think portrait mode is the best solution as you'll need the keyboard to play.

I remember to see some screenshots with a Nintendo DS emulation partially working (but can`t find that thread now) where both screens where put in landscape mode one besides the other, that seems a good approach.

Smoku, take a look at this thread:
http://talk.maemo.org/showthread.php?p=338493

You can take the bounty...