I don't know about you, but I can't wait for more hype. :P

I believe it. The original name was 400. Then they made some adjustments as they found more breathing room in the 300 than expected. The choice of adding 20 is probably in response to "they must be smoking something hallucinogenic." It's always fun when engineers/marketing/logistics have some fun with model names and "carve" their own little messages into their products. Another good one was when AMD put their Hammer logo beating some musical notes on a silkscreen for the demo Solo board. Those notes just happened to be the Intel jingle.

Argh...forgot to say that this would obviously be ATI's friendly nudge to Nvidia saying "Smoke THIS!"