Came across this article http://wiki.laptop.org/go/How_to_Damage_a_FLASH_Storage_Device on the OLPC wiki about some of the things to beware of when reformatting a flash device (USB stick or SD card -- what about SSDs?).

Basically, if there is a mismatch between the blocking of data at the filesystem level and the device page size, then you could be increasing the number of hardware-level writes by a factor of 2 or more. This leads to a corresponding reduction in the life of the device.