As I understand it, this is the current recommended setup for SSD drives.
Actually, I think even better than that is to use an SSD as a caching disk, backed by regular disks.
Then everything can benefit from the speed boost since the computer is better than you at deciding which files need a speedup. You don't want to move so many high write files off of the SSD that you make it pointless.
If you are on linux see: http://bcache.evilpiepirate.org/