I’ve been in the Midwest for the last 3 weeks, traveling around Illinois, Wisconsin, and Michigan with very few opportunities to get on wifi. Worse, most of the places I went to didn’t even have 3G coverage, forcing me to rely on the slow Edge, when available. I am currently in Chicago (for one last day before finally going back home to San Diego) where there is some very fast 3G coverage.
The first thing I did when arriving in Chicago was to enable tethering with this simple hack. It took about a minute to get it to work and to get my laptop going. It was the first time I actually tethered my iPhone 3GS and I have to admit that I am incredibly impressed with the speed.
I didn’t make any scientific test to see how fast it really is, but it seems to me that my wifi at home is not faster than that. Every once in a while there is a little downtime but nothing really annoying.
If you want to use your iPhone to get internet on your laptop (also known as tethering), I suggest you have a look at this hack.