AllThingsD is reporting that Apple will announce the successor to the iPad 2 at an event in San Francisco during the first week of March, citing anonymous sources familiar with the company's plans.
Previously, carrier profiles for the iPhone leaked March 9 as the release date for the next version of iOS— iOS 5.1. That squares pretty nicely with an early March announcement date for the iPad 3. Actual street date for the device would presumably follow shortly thereafter, if history tells us anything.
For a complete round up of what to expect from the next iPad, including a retina display and big battery life, go here.