In an attempt to figure out why a certain flash drive I have stopped working under OS X but continues to work under Windows and Linux, I found the wiki page How to Damage a FLASH Storage Device, which tells about how you have to be very careful where you place your partitions on a flash drive, in order to prevent the computer and drive from overworking themselves (e.g. if a logical sector spans two flash pages, not only those two pages but potentially all the pages in their erase block have to be read in, erased, and then rewritten). The page notes that devices already partitioned when you buy them (most are partitioned and formatted for Windows from the factory) are set up just right, but you risk low performance and short drive life if you partition one yourself without following its guidelines.
Is this true for off-the-shelf USB flash drives? I would think that if these problems were real and serious, partitioning programs (both open- and closed-source) would have been adjusted accordingly by now. (And SSDs I assume have their own set of gotchas which have also been worked around.)