Geoff Livingston has a great post called a the Five Forms of Mobile Media. Below is an excerpt but click on the link below to read the entire article.
1) Short Messaging Service (SMS)
2) Native Mobile Web Use
3) Applications: iPhone, Android, Blackberry, Windows… You name the OS, it’s hard to imagine that an application hasn’t been developed yet. Plus there is the whole tablet market. As Ken informed me, the applications marketplace is not the same as the smartphone market. iPhone applications are still very dominant with Android applications lagging behind in adoption rates.