Modern SSDs might not "fragment" in the same way your old 9GB FAT32 drive did, but they've got their own, possibly worse problems. OCZ, along with Indilinx, say they've got a "garbage collection" firmware that'll clear things right up.
Here's how it works, in terms that you may or may not understand:
The flash memory used on today's SSDs is comprised of cells that usually contain 4KB pages that are arranged in blocks of 512KB. When a cell is unused, data can be written to it relatively quickly. But if a cell already contains some data—no matter how little, even if it fills only a single page in the block—the entire block must be re-written.
In layman terms, that means that the way many SSDs write data is sloppy, and leaves all kinds of useless junk all over the place, which later causes slowdowns. OCZ has a firmware update that apparently fixes this while the dive is idle, and HotHardware says it's actually worth a nice little performance boost. So congratulations, OCZ SSD owners! Even better news?
Virtually all SSD manufacturers have incorporated, or soon will incorporate, garbage collection schemes into their drives' firmware that actively seek out and remove the garbage data.