Thanks to member Mazdachuck, who posted it in this thread, for this information.
PdaNet is definitely the way to go (as a couple of posters have suggested). Here's how to get it all working:
Follow this guide to Jailbreak your phone: http://www.iclarified.com/entry/index.php?enid=1881
Launch Cydia and search for "PdaNet" and install it on your iPhone
Create an ad-hoc network on your PC/Mac using this guide: http://www.junefabrics.com/iphone/faq.php#wifipc
Join your newly created ad-hoc network with your iPhone
Browse the web with your Carputer
I used this exact process (with a few Google searching in between) yesterday and it works great. PdaNet now works with Wifi (Apple/PC) and USB (PC) tethering.
Will this show up on AT&T as me tethering my phone? Because they charge an extra $20-30 for that and I haven't signed up for that yet.....
It currently wont show up as anything but data usage, but if ATT thinks that you are using it as a modem they will slap you with huge fees. There is no current tethering plan for the iphone.
Cant code cause I dont know how, but give me the paint bucket and my eraser and have at you!
thankyou for posting this I just got the i phone jailbroke it and am in the process of setting this up.
Just remember that if you are with o2 (UK) then there is a 200Mb allowance on the unlimited internet with the iPhone so browing is fine but just dont go download crazy