I also have not seen preorders go up yet in the US. My wishful thinking wants me to believe they are working out amazing preorder bonuses for all the retailers. But my logical thinking is telling me it may have to do with the fine print on the official US website that reads:
"*The Disney Infinity Base has not been authorized as required by the rules of the Federal Communications Commission. this device is not, and may not be, offered for sale or lease, or sold or leased, until authorization is obtained."
They are probably in the process of getting legalities out of the way before it can be officially sold in the US. I'm anxious to preorder!