Apple doesn't announce products at CES. If you haven't noticed they don't even participate in these events anymore. A lot of product gets announced at CES, but most of it doesn't make it to market (especially amongst the smaller tech companies who use CES as a way to raise funding). The iPad was announced and shipped one month later. A lot of CES tablets were announced and shipped 6-9 months later.

The $499 price point was absolutely devastating to every other tablet maker because up to then they were assuming Apple would price it at $800-1000. Which meant they could price it at 600-800 and have comfortable margins. Their announcement one month after CES sent everyone scrambling back to the drawing board.

Except for the Archos, I can't remember a single tablet from CES 2010.