This is something I've been thinking for a long while as well. If they bundle this with MobileMe for basic 3G (or even 1x/EDGE) cell access to email, iTMS, some select sites (wikipedia, to take a page from Amazon's book, and maybe a news site who is paying Apple for the placement, some limited version of a social networking site - Facebook or Twitter, etc) and leave complete internet access for WiFi only, it would no longer compete with the iPhone as a mobile internet interface, and still be a great additional tool for people with cell phone data plans. While I have ZERO desire to pay another monthly fee, a reasonable annual fee (~$100?) would be more palatable.
I agree. I am ready to buy IF the tablet has something new to offer AND does not have a redonkulous monthly cost. If AT&T allows me to share - or add for a small monthly fee like $5 - I can consider it. If it means another $30, that may be a deal-breaker.
I am off work on Wednesday, so I'll be at my Mac anxiously awaiting details with my credit card out - just in case.