For what it’s worth, I believe it’s entirely possible Apple might be holding back certain features so there’s something new to announce around the time it’s actually due to ship. In fact, there’s a precedent for this.
Shortly before the original iPhone was scheduled to launch in 2007, Apple announced two major (supposedly last-minute) improvements.
The first was a battery life upgrade (which was probably achieved by software improvements), the second was that they were “upgrading” the display to a glass screen – which seems like such an integral part of the overall device that it would have to have been planned all along.
My guess is that we’ll see one or two minor iPad announcements in March, but it probably won’t include a camera.