I have a iPhone4 through AT&T on the unlimited plan. I plan to buy the iPad2 very soon but am wondering if I buy the wifi model can I tether to my iPhone and be able to access the internet using the 3G network from my phone? I was told yes but I have to pay something like $50 a month. If that is the case then why would I even bother with tethering and just but the 3G iPad2 and pay for a monthly data plan? I am still a little uncertain on what tethering is. Is my phone basically sending my iPad a 3G or edge signal so I can access the net at anytime as long as there is a signal?