I had a nice conversation with Mark Schneider of Now Public yesterday about how to encourage their users to put more mobile content on their "worldwide citizen journalism newsagency" site. I wrote up a summary on the Bryght public wiki that is specific to Drupal sites like Now Public but generally applies to any website.
Here's an excerpt from: my wiki page (it's a wiki page, so feel free to update my typos and add other cool Drupal suggestions and modules!), How to Support Mobile Content Creation in Drupal:
The general rule should be to provide as many roads to Drupal as possible! The base technology (i.e. protocols like email, MetaWeblogAPI and Atom Publishing Protocol) are relatively "easy", getting something usable and useful on the mobile device is the hard part.