We’ve got a semi-experimental mobile portal for Wikipedia, based on the Hawpedia code using Hawhaw, that’s been up for a while.
I’ve updated it to the current version of the code, which seems to handle some templates better, as well as producing proper output for iPhone viewing. :)
Today’s fancy phones with their fancy browsers (the iPhone, Opera Mini, etc) can do a pretty good job handling the “real web” in addition to the stripped-down limited “mobile web” of yesteryear, but there are different pressures, which one should take into account when targeting mobile devices.
Screens are small, bandwidth is low. Wikipedia articles tend to be very long and thorough, but often all you need for an off-the-cuff lookup is the first couple paragraphs. The WAP gateway splits pages into shorter chunks, so you don’t have to wait to download the entire rest of the page (or wait for the slow phone CPU to lay it out).
Even on an iPhone capable of rendering the whole article and the MonoBook skin in all its glory, I find there’s some strong benefits to a shorter, cleaner page to do quick lookups on the go. (Especially if I’m not on Wifi!)
The biggest problem with the Hawpedia gateway today is that it tries to do its own hacky little wiki text parser, which dies horribly at times. Many pages look fine, but others end up with massive template breakage and become unreadable.
Long-term it may be better to do this translation at a higher level, working from the output XHTML… or else in an intermediate stage of MediaWiki’s own parser, with more semantic information still available.