doospunk, maybe you know as you work for ATT. Can't you already activate a plan to "teather" your iphone which would make it a wifi hotspot. I thought my iphone 3gs had an option to make it teather but I also thought it came with a price tag of 39.99/mo. I could be wrong about this but thought it was an option.
Edit: I found it. It looks like only an extra 20 on top of the datapro data plan which is 25/mo check you local att dealer for rules and eligability (did that last part make me sound like a corpo lawyer, haha)
http://www.att.com/gen/press-room?pid=17991&cdvn=news&newsarticleid=30854&mapcode=financial|Wireless
big motor guy - Yes, tethering is available for I-phone, but that only benefits you for areas that don't have wi-fi service and really only provides you the capability to connect your laptop to the 3G/Edge network associated with your data plan.
Maybe I misunderstood, but my interpretation of the original question was whether there is an app that would make the device a mobile "wi-fi" hotspot - meaning that the device provides the wi-fi signal to connect your PC to so your not drawing off your data plan. This is not an "apple approved" application today. IF their is an application that enables that, you'd need to jailbreak the device, but risk voiding your warranty.
On the flip side - The I-Phone is enabled with "WI-FI", meaning you can walk into any wi-fi hotspot (Such as Starbuck's/Carribou), pick up a signal, and revert from using your data plan. THe benefit to you is that the wi-fi is provided to by the retailer as an added convenience/attraction to their location. It also allows you to take advantage of that signal so that your not drawing off of your data plan. Once you leave that location, your device will revert back to the 3G/EDGE signal that your data plan is provided from.