PC Perspective's review of Intel's X25-M SSD, a custom-designed solid state drive, showed that the manufacturer's sector remapping actually lowered overall performance dramatically over time as the drive became irreparably fragmented.
Some background info. First, sector remapping—a custom solution from Intel— is a method that makes sure wear and tear on the drive is spread over the entire space instead of just in a small area (which would cause the drive to fail earlier). Intel's algorithm unfortunately makes files become fragmented eventually, and defragmenting software currently on the market just screw things up further.
Intel says it's working on a solution, but currently customers with the X25-M can only completely wipe the drive and start fresh in order to reclaim that lost performance. It's not a death knell to SSDs, since the problem can (theoretically) be fixed by either allowing defragmentation software access to the distribution algorithm so as to actually defragment, or having the SSD controller keep track of the fragmentation in the first place and try and minimize it. [PC Per via Ars Technica]