I've already made a post on the combination of your favorite feed on your idle screen. Several startups are looking at "non-intrusive" ads on the idle screen:
Celltick’s LiveScreen ‘bypassing operators’ with direct to consumer mobile ads.
what does that do the consumer I'm not sure, to see floating ads on your idle screen. Big yawn me thinks, and rightfully the Ewan writes "I’ve had more than a decade’s worth of experience of dismissing my phone’s standby screen whenever I want to ‘do’ something on it."
BTW, check out Cellogic, who are also in a similar space.
But what if...what if that idle screen had your favorite RSS feed, a mobile version of Google Reader, Facebook feed, including presence/location/mood updates from your contacts in your integrated address book?
There are enough kids out there burning idle time on various occasions between music (hum...publish a playlist from your phone...), games and much more. they would love the trigger from their friends through their social communities on the idle screen.
I think the idle screen is uncharted landscape that will go far. Far beyond advertising for sure.