Here’s a newly released app that can virtually turn your 3G iPhone into a mobile Hot Spot. The iPhone Modem App will tether your iPhone’s 3G connection to any WiFi enabled device.
Our source has tested it on both a MacBook and MacBook Pro and it works fine according to them. So, there’s nothing to indicate that the otherwise will be true with other capable devices. Don’t go looking for this app in the App Store, as the last tethering app we saw there was unceremoniously yanked off the shelves before interested users could download it. This is available through Cydia, which means you’ll have to jailbreak your iPhone first.
Just a word of caution; telecoms aren't usually delighted when the issue of tethering is brought up so if you decide to download and use the iPhone Modem app, just be sure that it’s okay with your provider or use it at your own risk.