Ed Bott's blog post on the subject is enlightening, but a bit late, seeing as I already went out and bought a 2 GB flash drive from SanDisk that simply does not measure up, making less than half it's advertised speed on several tests. (Having used a special discount coupon, I cannot return the device, either, and am taking things up directly with the maker. More on this as it happens.
Be sure to follow the first link in the post by Bott, which will take you to a post by George Ou with more information on the same subject.
And watch out when buying flash memory devices. I sure wish I had.