Lyle Bunn has written an interesting piece for Digital Signage Today. His thesis:

Social networking. Bluetooth. Mobile commerce. Millennials visiting Web sites and extending music and TV.  Each of these are components in the next wave of the digital signage business model.
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By extending display messaging to a personal device such as a cell phone, message engagement and brand interaction is significantly advanced. This advancement makes digital signage valuable for marketers and communicators wishing to extend ad display into brand engagement.

He gives us an example of this works with SMS Text Messaging:

SMS Text. Text codes presented in a digital ad could prompt the download of information, coupons or media such as ringtones, wallpaper or games. A text code could also enable a mobile commerce transaction. Mobile commerce provider mPoria reflects that the average mobile commerce transaction is $130 with conversion rates of .8-1.5 percent on mobile devices.

There is much more over at Digital Signage Today.