TR dealt with mobile gaming few weeks ago (because of the GDC). The article was about the (possibly) biggest problems in the field: a lack of standards:

"The mobile-phone environment unfortunately has been driven by the service providers, and they have different demands for what technologies can and can't be used," says Michael Zyda (...) "It's a crazy era, much like the early days of computing, when each manufacturer was making their own operating system and there weren't standards for interoperability,"

TR describes the fragmentation caused by hardware and software issues: presence of different physical controls (button placement), different software platforms... leading developers to test it on "12 platforms" (I quote it because my feeling that the correct number is 1000). The problem being that... companies do not really want to standardize stuff ("They want to lock you into the way they do things"), so it's still about walled gardens. Game designers (like the ones at Shufflebrain) then rely on networks rather than on cell phones. Why do I blog this? stuff for my presentation next week at Mobile Monday, Bcn, about mobile gaming (and its crux need for new metaphors).