“Seamless mobility” is a trendy industry buzz phrase, promoted by Motorola, Microsoft, Intel and many others. Any content available on any device across any network…sounds magical! Often this idea arises in discussions of fixed-mobile convergence. Yet systems that successfully span fixed and mobile are usually not seamless at all. On the contrary, fixed and mobile remain distinct, each optimized for its own constraints. Consider two highly successful systems, the Apple iPod and the RIM BlackBerry.First, neither system attempts to create a universal experience for accessing any content. On the contrary, each is optimized for a particular compelling experience, listening to music or podcasts on the iPod, and tending to business email on the Blackberry. Each experience is concrete and easy to understand, not abstracted into universal techno-speak. “Listening to music” and “tending to email” are much more tangible than “a new world where consumers are mobile, informed, entertained, secured, connected and empowered” (sorry, Motorola). Future examples might include “watching television,” “playing games” or “attending meetings.” Focus on experience seems central to Apple and RIM’s success. Second, neither attempts to create an identical, “seamless” fixed and mobile experience. Using an iPod is different than using iTunes, and using a Blackberry is different than using Outlook. And the experiences should be different. With iTunes and Outlook, the user is sitting down, gazing at a full screen, and using both hands on a keyboard and mouse. With an iPod or Blackberry, the user is on the move, glancing at a small screen, and often using only one thumb on small buttons. Rather than seamless, these experiences are coherent. They are the same in ways that make sense, and they are different in ways that make sense. My songs and podcasts in iTunes also appear on my iPod. When I delete email on my Blackberry, it’s also deleted when I look in Outlook. Much of the art of such systems goes into designing every detail correctly, maintaining this coherence. Hand-waving about “seamlessness” neglects these all-important details. Finally, the coherence of each system flows from a single source of definitive data. For the iPod, that source (of song files) resides on my Mac or PC with iTunes, and coherence is maintained through syncing the iPod periodically. For the Blackberry, that source (of emails) resides on my Exchange server, and coherence is maintained through the cellular data network. As Internet connections become faster and more ubiquitous, I expect that such sources will increasingly reside “in the cloud,” that is, in professionally maintained data centers, rather than a personal computer (more like the BlackBerry than like the iPod). That way, maintenance and back-ups don’t burden the user, and data stays current rather than drifting into obsolescence between syncs (particularly noticeable with podcast subscriptions). In fact, if I were the Microsoft Zune product manager, I’d shift towards the cloud model and away from the sync model, in an effort to differentiate from its current imitation-iPod positioning. Both these examples require specialized mobile devices, but with the emergence of more open mobile devices, perhaps developers will create new experiences on such platforms instead. Either way, the key question is not whether they support seamless mobility, but rather whether they create a coherent experience. With offerings from big companies, like Cisco’s Unified Mobile Communicator and Qualcomm’s MediaFLO, to start ups, like MobiTV and Danger, users have many new experiences to try.