Foruming on mobile phones is pretty hard as you can't exactly write well/long on mobiles.
Also, that link goes to a developer that uses the iPhone and Android systems, and that means the foruming would be very limited. It also looks like to be able to use that app, AG would have to completely recode the forums. There's no point in that...
This discussion has been had several times before and each time it has been decided that it just isn't worth the time and money to further simplify an already simple forum for cell phones. The layout shouldn't be a problem on most phones anyway, so I don't see a problem.
I am using my friend's iPhone right now to post this. There is a mobile website for the website itself, all you have to do is scroll to the bottom and click "full website",'or something along those lines, then just click community!! I've done it a couple times actually! If I don't make sense, that's probably because it's 11:15 at night and I'm tired, hah.