Nokia recently (May 29, 2007) released Version 1.0 of a document describing the guidelines to develop Mobile Web sites specific for their devices, of course. The document is specifically aimed to developers and authors that want to target the most recent and advanced mobile browsers, based on Apple’s Webkit. The document is called “Nokia Web Browser Design Guide” and you can download it for free (after registering) from Forum Nokia.
It is good to see another big company, shortly after Ericsson, to suggest WURFL.
Andrea Trasatti's tech notes and more 