If I may, I'll piggyback (certainly no intent to hijack) on the OP's statement, as I just logged on in order to research this exact issue.
I just verified my cable modem and wireless router are working properly, yet on two 6 month old Macbook Pro's (15" and 13", respectively), wifi is pathetically slow (we're talking 1-2 Mb/s, where via ethernet I'm getting around 22 Mb/s). I'm about 8 feet from the router. I also have Win 7 via Bootcamp on the 15" and have the same results. Two laptops purchased together, same issue? I have to assume it's and update-related thing. Bluetooth has no effect on the results, as well.
My two and a half year old Dell Inspiron is pulling around 22 Mb/s wirelessly, no issue. Same with the two iPhones, and the 27" iMac I'm typing on at present.
Nothing like sitting on $4k worth of laptops that can't even pull 2 Mb/s from a wireless-N 24 Mb connection. Hope we can figure this one out soon. I'd hate to have to set up an appointment with the Genius Squad.
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Also, I have yet to attempt to connect to another wireless router and re-test. I have little confidence it will have any*effect, yet I'm sure someone will, invariably, ask.