What that means is that you will be able to use your iPhone as a wireless modem for your computer to connect to the Internet (over 3G where available). I had this with my Treo, where Verizon Wireless charged me $5 more per month to add the “tethering” package. But now, with the iPhone and AT&T, I was unable to do this (at least legally). So I had to buy a wireless broadband card from Verizon Wireless to make sure I have Internet access on my laptop everywhere I go.
I will “soon” be able to drop the Verizon Wireless service ($60 per month) and just add on a tether option to my AT&T iPhone plan. Can’t wait!