iPhone tethering - opportunistic plan?

So "later this summer" AT&T will announce the iPhone tethering plans. For those of you who don't know, tethering means being able to share your phone's internet connectivity with your laptop either through bluetooth or over a USB cable.

if you ask me, it's likely to be about $30/mo. for all-you-can-eat tethering. Why? Because the unlimited data plans for USB dongles are about $50, but the value proposition is a bit lower with the iPhone because you already have Safari and other network connected apps right on the phone itself.

Even when all I had was the iPhone 1G with EDGE, I found that I stopped taking my laptop with me on trips. I just loaded some movies into the phone to watch on the plane and surfed with EDGE and WiFi. But the phone can't do everything. I can't play online poker on the phone or watch Netflix instant watching. The last time I was stuck in the hospital, I borrowed a Verizon data dongle from a friend of mine so that I could do those things.

In short, it's not worth it for me to pay monthly for a data connection for my computer. No, what I want is to be able to buy a "day pass" of unlimited tethering for something like $4.99.

If AT&T offered that as a feature, they'd probably actually get a lot more money than they would with monthly plans. Take a look at my hospital stay: I was stuck in the hospital for 5 days and part of a 6th. At $5/day, that would have been $30 - what they'd probably expect to get for a full month's worth of service. And it would be worth it for me, because I normally don't need to have tethering at all. But when I do need it, I'm willing to pay about that much for it.

They'd also profoundly impact the WiFi hotspot market, where the price for day passes at places like airports can exceed $10 (in theory, the airport internet connection over WiFi would be faster than 3G, but that's not always the case in heavily congested public places like airports).

So how 'bout it, AT&T?