Just finished browsing through the latest issues of Library Technology Reports which someone at ALA kindly sent to me. Written by Ellyssa Kroski (iLibrarian and InfoTangle), On the Move with the Mobile Web: Libraries and Mobile Technologies does a good job of providing background on the state of mobile (aka cellphones for the most part) technology and trends in the US. Even if you're in a different market you'll find good information here. I was particularly pleased to see the final chapter include starting points for making your own website mobile-friendly. Something else to add to the list of things to do! Oh, and it looks like you can download the first chapter as a PDF from the ALA site.