Russell Beattie has an interesting piece about CSS for mobiles and how it will less and less make sense to build different markup for mobile devices, but instead just adjust the CSS.
In the longer (resp. hopefully shorter) term, he's certainly right. Today's mobile browsers (like Opera Mini and my native k750i browser) can handle handheld CSS just fine. But for the average mobile user, who pays for every kB downloaded a ridiculous amount, it's still not the best solution. But the mobile carriers are now introducing not-real-flat rates for somehow reasonable prices and with EDGE, UMTS and whatnot, the mobile internet will soon be āfast enoughā and the day of different html for different devices are outnumbered :)
With Flux CMS we currently use both modes. Handheld CSS for the ānormalā html pages and a link to a special mobile mode, which removes some content server side to avoid having to download large amounts of unneeded data. Here's the whole story.
Russell Beatttie proposes also doing something like CSSZendGarden for handheld CSS. Great idea, since that area is almost unexplored (or I just didn't discover it until now)