Tether is an application (2 apps – one for your Mac/PC and one for your iPhone/BB/Andriod) that allows you to share Internet access from your phone to your laptop (or other wifi device) using your smartphone’s data plan. No need for jailbreaking or paying extra for WiFi hotspots or data “tethering” plans.
I have not tried it yet but will soon – I wish I had know about it before I gave up my unlimited data plan. They have had a real battle with the AT&T/Apple corporate control … But they came up with a innovative technical solution. Reminds me of how the clever Dropbox guys hacked OS X core to get their amazing technology to “just work”.
Tether’s new version for the iPhone is purely based on HTML5 and creates a completely wireless connection over AdHoc. This circumvents the need of buying the application directly from Apple’s App Store and allows any iPhone or iPad with a data connection to allow tethering.