Microsoft finally revealed Windows Mobile 6.1 at the CITA Wireless event in Las Vegas on April Fool's Day.

This much-trailed update to Windows Mobile 6.0 presents a range of new features. Still, it's more about enhancing the existing functionality of Windows Mobile than doing anything revolutionary, and overall the update smacks of playing catch-up with the competition. For a really big overhaul, we'll have to wait for Windows Mobile 7.

The few developments unique to Windows Mobile 6.1 Standard (for devices without touch-screens) narrow the gap between it and Windows Mobile Professional devices.

If you have an existing Windows Mobile 6.0 device, keep an eye on your vendor's web site for notification of ROM updates. New devices running Windows Mobile 6.1 are expected to appear during the second quarter of 2008 — any time from now on, in fact.

Much of the look and feel of Windows Mobile 6.1 is familiar, but there are plenty of changes under the surface. The Today Screen, for example, now has a plug-in which Microsoft is calling the Sliding Panel.

This uses a series of horizontally scrollable screens that allow you to move through related information. The theory is that you can get to more information more quickly using this system than you can with a 'flat' screen.

Then there's threaded SMS messaging. This is hardly a novel idea, and its appearance natively in Windows Mobile is long overdue. With threaded SMS messaging you can view text messages as if they were a single continuous conversation, which allows you to follow the ebb and flow of a chat more easily.

Internet Explorer has had an overhaul too, and as with SMS threading it simply brings features that have been available elsewhere to the application.

Flash and other rich-media features are handled better, for example. Owners of Windows Mobile 6.1 Standard (no touch-screen) devices will be able to set their own home page just as Windows Mobile 6 Professional (touch-screen) users can already do.

The zooming system has been refined too: text size changes are replaced by five levels of zoom in an effort to help with reading more complex web sites and allowing you to get more of an overview of some pages.