The new generation of Ultrabooks has been relatively slow to adopt the always-connected model, as surprisingly few units are shipping with built-in cellular broadband. As true 4G networks become more widespread, that might change, especially as cloud storage becomes more integral to the operating system. Apple is already pursuing this idea with iCloud, and Microsoft will be integrating its SkyDrive service into Windows 8.

Ultrabooks are only one response to the changing market, though. Microsoft’s new Surface tablets show how PCs are evolving in other directions. The Surface RT model is locked into Microsoft’s app store, much as Apple’s iPad is locked into iTunes. But the Surface Pro is really an ultrathin PC in a tablet skin, with a fully functional Windows desktop and the ability to run most Windows applications.

While the notion of running software from the cloud isn’t new, it is gathering steam. Google has led the charge, and Google Docs has seen rapid adoption. Microsoft has been pitching Office 365 (a collection of hosted productivity apps) to businesses. Even games are running on the cloud, with companies such as Gaikai and OnLive offering games on cloud servers and delivering interactive streams to user desktops.