Flash memory devices have a write-erase life cycle of between 100,000 and 1,000,000 sets. I never thought of flash memory as being limited to the number of times a section of the media could be reused; I assumed that the media would be similar to hard disks, which fail mechanically before the media loses its ability to store and retrieve data.
The limitation came about because the device was used as a first-tier storage device for a portable Microsoft Windows installation. The swap file was continually writing and erasing temporary data files, and after six months, the media gave out.
See the Limitations section of http://en.wikipedia.org/wiki/Flash_memory.