Above is the snapshot of downloads across the world at 1.53 PM IST on June 18 2008. According to details on this page: US had 2,095, 322 downloads and India downloaded just 42,770 times.
I downloaded it in my office, which has actually got a US IP address and I guess many people in India downloaded it in their offices and that counted towards US's downloads. Internet penetration in India is still very low and mostly people access net in their offices only.
I am not saying that all office downloads swelled US numbers or the cause of a huge US number is due to us only, but this could be a significant number.
I don't know if FF3 has created a record or not, but the fact is that record or no-record, FF3 is a better browser in all aspects!