I just bought a 64 gb iPad 1 from the AT&T refurb store/premier and I currently have an unlimited plan for my iPhone 4. I plan on downgrading to the iPhone 2 gb plan and use tethering on my iPad 64 wifi/3G for situations where I really need it. Basically, I want to find out how seamless it is going from the 2 Gig plan to the 4 Gig tethering plan and back to 2 Gig via the ATT iPhone app. I mean, will it take awhile for it to update to the account or is it something that takes a full business day? The reason I'm asking is because I'd only have to pay the pro-rated 4 Gig tethering plan for when I want to use my iPad for tethering. If any of this is a bit foggy I can clarify it. FYI, the most data I've used to date is just under 2 gigs but it'll go up when I use the iPad for tethering.