When AT&T CEO Ralph de la Vega dropped word that they have official iPhone tethering for data access in our future, we only had one question: how much?

Well, MacBlogz [via Giz] brings word that they expect it will be $30 a month. This certainly seems reasonable (the rumor, not necessarily the rate) as Giz notes that it matches the current tethering plan made available for BlackBerrys. It looks as though iTunes will further recede from being 'just a music player' as it will also handle your tethering setup.

As you might expect, it will be capped at 5gigs a month, which seems pretty anemic for $30 bucks to us. On the bright side, PdaNet has sent in word that they're still hard at work on their excellent tethering application -- we suspect that translates into "make it even tougher for carriers to detect that you're tethering."

So basically: AT&T wants to charge you $30 per month for a plan that can only be used for occasional tethering. It's what we expected, sure, but it's not what we'd hoped.