10:50 AM -- It took a little while, but you can now buy wireless data "day passes" from any of the three major carriers in the U.S. for $15 or less.

AT&T Inc. (NYSE: T) became the latest major mobile operator to offer a data day pass for laptop users on its 3G network. The GSM operator says users can get on with any compatible 3G laptop or netbook. They just need to buy a new SIM card from an AT&T store and fill in a customer profile online.

The carrier is charging $15 for one day with a limit of 75MB downloaded; one week costs $30 for 250 MB; and $50 for one month nets you 500 MB. Clearly, these megabit limits mean that the plans are more suitable for simple email downloads and Web browsing, rather than online gaming or music downloads.

AT&T's new day pass is priced to directly compete with a similar offering from Verizon Wireless . Just like AT&T's offering, the Verizon Mobile Broadband day pass starts at $15 for a 24-hour connection.

The big two are following smaller rivals -- Sprint Corp. (NYSE: S) and Clearwire LLC (Nasdaq: CLWR) -- into the day-by-day business. Sprint has been offering a $9.99 day pass since 2008 but only on the Clearwire WiMax network.

Sprint, however, doesn't have a daily plan for its 3G CDMA network. The carrier currently offers a 5GB a month service for $59.99.

— Dan Jones, Site Editor, Unstrung