This photo shows Apple's iPhone 3G alongside two other new devices, the HP iPaq 914 and Nokia's E71. As the picture demonstrates, they are all approximately the same size, although varying in weight and thickness.

All three devices represent the latest technology, supporting 3G wireless broadband, Wi-Fi, and GPS capability for navigation and other location-based services. As such, these are all high-end devices and potential rivals for RIM's BlackBerry models in the enterprise.

Of the three, the Nokia E71 is the slimmest and the lightest, while the iPaq 914 is the heaviest and thickest at 154g and 16mm. However, it also appears to have the largest battery capacity, at 1940mAh.

The Nokia E71 has already been reviewed in depth by IT Week here. To sum up: it is a very capable business messaging handset, but its keyboard is somewhat cramped compared to a BlackBerry.

The same criticism can be levelled at the iPaq 914, but I found I could enter text fairly easily. The HP device also has one feature that might please BlackBerry users; a jog dial thumbwheel on the right side of the case, similar to that seen on older BlackBerry models before RIM introduced its 'Pearl' mini trackball. It also supports touch-screen input via a stylus as well as a standard five-way navigation control, giving users more input choice than most devices.

Apple's iPhone 3G has the best display and offers the best web experience through its Safari browser, but has two drawbacks as far as I'm concerned; no keyboard and a battery that cannot be removed by the user.

As with the first iPhone, the device is very simple to use, but I found Apple's on-screen 'soft' keyboard a pain - even compared with the tiny keys on the E71 and iPaq 914 - and kept finding myself hitting the wrong letter. The iPhone could prove a hit with business users that need a decent browser - such as for web-based applications - but I can't see heavy email users or anyone whose job entails entering a lot of data being happy with it.

All three models feature some form of assisted GPS (A-GPS) to speed up the time it takes to get a fix on the user's location. While the E71 has Nokia Maps, both the iPaq 914 and the iPhone use Google Maps. The iPhone version of this application is slicker, but both have pretty much the same functionality, including the option to fix your location GPS and get directions to a specified destination. However, Nokia Maps supports turn-by-turn directions for drivers, although it costs extra to have the directions spoken aloud.