Linking to a stylesheet with media=â€?handheldâ€? and other XHTML template approaches would be ideal in a perfect world, and in no way am I suggesting that sites should not do that as part of their mobile solution.
Unfortunately, not all 2 billion plus mobile phones in the world support XHTML MP / CSS, and the ones that do so offer varying support for those standards. There are also issues of a specific phones media support, screen size and network speed. Throw into that mix the notion that 1.) Perhaps browsing is not necessarily the best use case for mobile users and 2. ) Perhaps you wish to have your mobile site take advantage of the fact it is being viewed from a phone by interacting with phonesâ€™ inherent features.
If anyone wants to explore this topic more, Cameron Moll has done a great job offering insight and options in this series he wrote on mobile web design:
Mobile Web Design: Methods to the Madness (which contains a great chart comparing various methods)
Mobile Web Design: Tips & Techniques
From my perspective it is more than just publishing content (Separate set of templates) to a mobile environment or automagically squeezing a Web site onto a small screen (Opera Mini). It is about the individuals it engages, the people it connects, the dialogue that develops, the community that forms and the collective action that can result. Providing mobile solutions with this in mind requires more then stylesheets and transcoding services to get the job done.