Tether is an application that allows your Mac and PC to take advantage of your smartphone's data plan, providing you access to the Internet on your laptop anywhere there is cellular coverage from your smartphone.
Tether is easy to install, easy to use, works practically anywhere, and is very cost-effective.
To download the PC software visit:
http://tether.com/i/Tether-iPhone.exe
To download the Mac software visit:
http://tether.com/i/Tether-iPhone.dmgIt is certainly possible that Apple pulled this app when carriers of the iPhone objected to their approval of this app. This seems likely because Apple asked the developers a lot of questions and asked for a demo, so they certainly knew what the app they were accepting was capable of doing. However, carriers have been known to hate free tethering apps. A few months ago, AT&T started to send out text messages to users who had been illegally performing free tethering on their iPhone by jailbreaking it and using apps like MyWi that can only be downloaded on jailbroken phones.
This scene seems almost identical to 2008, when Apple approved a similar app called Netshare that allowed you to tether devices to your iPhone, but very quickly pulled it. In a few years, Apple would allow tethering on the iPhone, but only with additional plans starting at $20/month.