The dotMobi WordPress Mobile Pack
It looks like this new plugin is trying to be the most complete solution for a mobile WordPress experience:
…includes a mobile switcher to select themes based on the type of user that is visiting the site, a selection of mobile themes, extra widgets, device adaptation and a mobile administration panel…
I like how it provides both front-end and back-end mobile version of your WordPress. You can also check other plugins made for mobile purposes here.