mPage version 1.1, one of the leading Moodle Mobile applications was recently released by developer, Mass Media of Hong Kong. Version 1.1 supports InApp purchasing of upgrades and functionality for the Mobile app. InApp capabilities include a functional forum module (which in the free version is read only). For more information about the InApp upgrade road map visit:
http://mpage.hk/mod/resource/view.php?id=110
To see the forum activity in action visit http://mpage.hk/mod/resource/view.php?id=119. (Note that while the app is free, Paid mPage Upgrades [PMUs] are ~$0.99 each.)