SMS as a modality for public health communication is so 1.5+ years ago. It's trendy and effective(!) in Africa and certainly applicable to other rural areas of the world (mental note: remember this for vaccination projects in greater China as well as Vietnamese communities beyond Hanoi and Saigon). In case you're interested in hopping on the bandwagon, here are good resources I picked up from attending a NetSquared presentation featuring Ben Rigby:
Anyhow, and beyond that, according to a Wikipedia entry on mobile advertising:
"Other forms include MMS advertising, advertising within mobile games and mobile videos, during mobile TV receipt, full-screen interstices, which appear while a requested item of mobile content or mobile web page is loading up, and audio adverts (eg, in the form of a jingle before a voicemail recording)."
Throwing down the gauntlet to myself and others to flesh out these other forms of mobile public health PSAs.