Majority owned by Sprint-Nextel, the Clearwire service currently offers flat priced services for laptop wireless connectivity, but recently stated plans to develop a pay-as-you-go plan. From a brief Reuters article,

Clearwire is the first U.S. service provider to offer fourth-generation wireless services but its biggest rival, Verizon Wireless, is expected to follow suit with a 4G service later this year. Verizon Wireless is a venture of Verizon Communications and Vodafone Group Plc.

While different pricing models will greatly benefit consumers—I know that it does for me, with a lot of phone companies selling mobile hot spots—the competition of also breaking into 4G from 3G should help lower entry prices.
Without pricing to report, we can only speculate that pay-as-you-go buffet style wireless will end up costing more per-meg than flat-rate pricing; but with the benefit of not incurring gigantic overage prices on excess. However, with several wireless carriers offering unlimited plans, it will be interesting to see where this falls in the wireless subscription ecology.