Mobile telephony adoption is on the rise, with industry projections suggesting that wireless subscribers will reach 1 billion worldwide by 2002 [3]. Recent technological innovations have also dramatically enhanced the capabilities of the wireless telephone [8]. No longer restricted to voice communications, wireless devices are now also able to transmit and manipulate data. Leveraging the power of these new technologies, various business sectors are working together to offer a wide array of services, including voice communications, short messaging, information services, web surfing, location-based services, and e-commerce. Each sector is looking for the next "killer application," yet we are still learning about people's information and communication needs while "on the go" [9, 10, 11 ]. Additionally, it is difficult to anticipate what new possibilities or challenges are created for the user upon the introduction of these new computational capabilities. An understanding of these issues is critical to the CHI community's ability to produce good technology - technology that is innovative, useful, usable, and profitable. Copyright © 2012 ACM, Inc.