For that matter, we could cast our minds back to the other protoypes that were shown at CES 2010 in early January 2010, before we got to see the iPad. For example, the Asus Touch:
http://www.slashgear.com/asus-eee-pc...-2010-1369731/
I can't seem to lift out the image URL from that link, but the article again indicates that companies were intending to release tablets with the obvious flat design with black bezel and rounded corners even then, because it was an obvious design choice and the technology had improved to the point that it was possible.
Graham