Tablet PCs have firmly established themselves in certain vertical markets where users don't have offices or need to compute while standing. But as the tablet market matures, more sedentary office workers could benefit from using them, particularly when it comes to annotation and approval tasks. This presents opportunities for solution providers to spread the message about tablets.

According to IDC research, tablets doubled their market share in 2007 from 2006, accounting for more than 7 percent of the mobile market last year, and they are on a similar growth curve this year. What has changed to make tablets more popular? Three things.

First, as more office workers tote hardbound diaries in and out of meetings to keep track of commitments and to-do lists, tablets can play a more useful role. "I have a really bad memory, so I take a lot of notes in meetings," says Seth Fearey, Smart Valley Initiative director at Joint Venture: Silicon Valley Network. Fearey has been using a Fujitsu tablet for more than three years and says he loves the built-in journal software: "I never run out of paper or ink, and easily erase and add notes."

The journal application is just one of many general-purpose applications that can record handwriting and allow fast text searches. The ink-recording feature of tablets can be useful for preserving diagrams, making quick sketches, and annotating PowerPoint slides and documents. This feature captures real-time meeting notes that can be shared with all participants.

Second, there is now wider and deeper support for tablet-style applications that can be used by general office workers. Windows Vista now includes tablet support for all enterprise-level versions, and its support is better than what was previously available for Windows XP.

Vista's tablet features also offer two important improvements over the tablet XP version: handwriting recognition and pen navigation, the latter being supported more completely throughout Vista and not limited to just a few applications and menu commands.

Finally, the tablet market has matured into two subspecies: the slate and the convertible form factors. Slates are geared for applications that don't make use of the keyboard as their primary input device, although they can be fitted with optional USB keyboards in a pinch. Convertibles tend to be used in office environments, are heavier and come with attached keyboards. Typically, they have a rotating screen lid that can be positioned face up or down as the user switches between pen- and keyboard-based applications.

Another positive sign: Dell entered this market this year with its Latitude XT model, a move likely to help keep prices down and widen the tablet's reach. The two best vendors for VARs are Motion Computing, which sells only slates, and Fujitsu, which sells both kinds of tablets. Both have well-developed reseller programs.

There are opportunities for hardware VARs as well as software developers that specialize in construction applications that run on tablets, such as Vela Systems.

Allegiance Technology Partners is a tablet specialist that carries several models and offers a liberal four-day return policy. "You can't go into Best Buy and see a tablet PC. People had concerns, and people very rarely return these units," says John Hill, the company's CEO. "It is a fun product to sell, and the margins are better than with traditional desktops."

Yes, tablets are becoming more popular, and as the applications mature and the price premium over ordinary laptops disappears, expect to see more of them purchased by corporate IT managers. Now is the time to get into this channel.

David Strom is a technology freelance writer, consultant, blogger and podcaster and can be reached at david@strom.com.