I think most websites do that. The point is functionality. I use mobile internet for email, gps, news (bloomberg and reuters only) and sports sites, basically I am an information user. I know ppl use it also for social networking or entertainment maybe (don\'t know if you realized AT&T users can no longer have unlimited data plan), so the industry is very dynamic and i guess the market position of your site is more important than any other factors, cz\' there are always tons of websites, but you may not need to look at all of them.
I develop it as a CMS (contents management system) . a online shop ,BBS ,a book library and a mobile online game have been added to the system as a add-on module.