Yes. Users have reported that USB audio headsets work with the iPad. To connect a USB headset to the iPad you must have the Camera Connection Kit accessory.
The Camera Connection Kit adapters plug into the Apple 30-pin dock connector port. One of the adapters has a USB port that is officially advertised as a way to connect your digital camera directly to the iPad. Connecting a USB headset to the adapter works, although the iPad will not indicate that audio has been switched to the headset.
Not all headsets will work. Apple officially does not support the use of the Camera Connection Kit for anything but digital cameras.