I do not believe a iphone app (or android for that matter) has been made for this forum, nor does it appear to have a mobile version of the site. Do you find you would like an app for the site?
The site seems to work well (visual) from iPhone now-I am using iPhone now. I really do not know the long term plan of this site so I would not know how to answer that. If it brings in more users, sure it would be a good investment.