Mobile devices have come a long way since the days of the first Palm Pilot, or, for those with longer memories, the Psion Organiser and other 1980s pioneers of handheld computing. Today’s devices have wireless communications, colour screens, and the capability to run applications just a step down from those found on desktop PCs, but has their evolution now stalled?

I was mulling this point while helping out with the Mobile IT supplement that accompanied a recent issue of IT Week. Some of the newer smartphones and wireless handhelds on the market support the HSPDA extensions to 3G networks, enabling download speeds up to 1.4Mbit/s, which isn’t lagging far behind many fixed-line broadband connections.

The question is; what are users going to do with that bandwidth? Few mobile applications would max out a 3G connection at the moment. It’s always good to have a fast connection to browse the web, but what are you going to do on a device with a 3.5in screen that would require a large amount of data? There is the mythical market for mobile TV and video-on-demand, of course, but this is strictly a consumer application, unless being able to watch the football anywhere is one of your business goals.

The size limitation, rather than technology, seems to be constraining mobile devices. How do you squeeze in a decent-size display and keyboard, without ending up with a product that rips open the user’s pockets? In fact, devices have tended to get larger rather than smaller in recent years, precisely because of the difficulty of reading web pages on a tiny screen.

Designers have settled on a handful of device formats: the BlackBerry style with a qwerty keyboard beneath the screen; the candy-bar smartphone design; the clamshell design; and the traditional PDA style with a touch-sensitive screen. Each is a compromise in one way or another – for example, the BlackBerry format trades display area for a keyboard.

Meanwhile, new types of device, such as the Ultra-Mobile PC (UMPC), are starting to appear. These hold the promise of access to full-blown Windows applications in a device not much larger than smartphones and PDAs. But early UMPCs also suffer from size restrictions, a cripplingly short battery life and a distinct lack of processing power by comparison with laptops. The early models also have a non-standard letterbox display format, which seems geared towards widescreen video entertainment rather than business applications.

What is needed in mobile devices is innovation in the user interface to allow devices to break out of the limitations of their small form factor and become easier to use. One possibility, hinted at by Sony Ericsson’s chief technology officer during a presentation at last month’s Symbian Smartphone show, is the development of fold-up displays.

Also needed is a new generation of batteries that can supply greater power to meet users’ demands for Wi-Fi, Bluetooth, and 3G data connections, and operate a GPS receiver all at the same time. Otherwise, further increases in computing power will be in vain.