In the near future, customers will be able to use Apple’s iPhone 3G as a wireless modem for computers, an AT&T (NYSE: T) executive said.During an interview at the Web 2.0 Summit in San Francisco, AT&T Wireless CEO Ralph de la Vega said Apple and the wireless carrier are working on an official tethering application that will be coming “soon.”

The AT&T executive did not give a clear timeframe for when the app was expected, but a rollout in 2009 appears to be likely.Users of the iPhone 3G have wanted to use the handset’s high-speed connection with a laptop or desktop for a while, and developer Nullriver created an application to fill that need in July. The application, NetShare, was pulled, returned, and then finally banished from the App Store because it violated AT&T’s terms of service.

The wireless carrier offers tethering plans for many of its smartphones, including BlackBerrys, but currently not for the iPhone 3G. Unlike the NetShare application, an official application will most likely cost a monthly fee.

The ability to tether also has been one of the main draws for “jailbreaking” the iPhone 3G, and there are multiple unofficial tethering apps for unlocked iPhones. But customers risk their handsets being “bricked” by a software update, and AT&T could potentially charge users for breaking its rules.

“Furthermore, unlimited plans (except for Data Connect and BlackBerry tethered) cannot be used for any applications that tether the device (through use of, including without limitation, connection kits, other phone/PDA-to-computer accessories, Bluetooth, or any other wireless technology) to laptops, PCs, or other equipment for any purpose,” AT&T’s terms of service for the iPhone states.