I'm not sure how many iPhone user are out there that use the forum. But for me, using the native safari to browse the forum can be tiresome at times. Especially with zooming in and out.
Over this week I've been testing a new free app from the appstore called TouchBB. To get it to work I had to install a small file to the server then we were working perfectly.
The app costs nothing for the lite version, and works like a dream. Definately makes browsing the forum on the move alot easier.