A Waltham, MA, company called ZINK ("Zero Ink", www.zink.com) is promoting a technology that embeds heat-activated CMYK microcrystals within a durable, water-resistant paper stock. Digital images can be exposed on this stock using extremely compact printing devices—possibly compact enough to be built into camera-equipped cell phones. That's ZINK's primary target market: people snapping untold numbers of shots with their camera phones, which soon will outnumber conventional cameras as picture-taking devices. This video from Demo.com gives a good overview of the technology (runs 6:41):

Here is a smaller clip from Gizmodo:

Short commercial for Zink printer:

A commercial for an integrated camera/printer: