Actually, as of December 2012, the selected answer is partially wrong. I am getting ready to buy the Netgear R6300 (1750 AC) router. It is a draft wireless gigabit router. So, at this time, yes, there are routers (Netgear, Linksys and several others) that support higher than the USB 2.0 spec - which means that the USB wireless makers need to make some of the USB adapters with USB 3.0 - As of Jan 2013, I have yet to find any USB 3.0 USB wi-fi adapters (checked Amazon, TigerDirect, Best Buy, Wal Mart, New Egg and MicroCenter - nothing yet).
FYI, USB 1.0 tops out at 12 Mb/s (that's mega-BITS, with "little b" - I hate it when someone says something like 12MB/s - because that is TOTALLY wrong - "big b" means BYTES - which would be 8x more than the "little b" (bits).
USB 2.0 tops out at 480Mb/s, and there are a BUNCH of USB wi-fi adapters that "claim" N600 (i.e. 600Mb/sec) and N900 (900Mb/sec) and even the newest Netgear that I just bought that claims dual-band max of 1750 - i.e., 1.7Mb/sec) - BUT this is FAKE! Why? Because ALL of them are USB 2.0, which maxes out at 450Mb/sec.
Granted, if I can get about 400Mb/s, I'm generally happy. Still, it is FALSE ADVERTISING to say we are getting OVER 480 Mb/s (which the UI [User Interface] for these wi-fi devices will claim), when we know that the limit is 480. Now, I'm sure someone will chime in and say there some sort of "packet compression," allowing us to get more than 480Mb/s on a device whose limit is right around 480Mb/s, but I don't know that I buy that. I want to see some 'real-world' tests.
So, the manufacturers are lying to us. Agree or disagree?