I recently reconfigured my MacBook Pro (of RAID fame) to use an MTRON MSD 3000 32GB SSD drive as a boot / apps / Aperture database drive, plus my existing 160GB ATA/IDE drive as a second data drive (and overflow application area). Everything SCREAMS now, and I couldn't be happier. I'll have a detailed report on all of this (including benchmarks, videos, and subjective commentary) as soon as possible; there is too much going on right now to do it this week.
But check out this video of Aperture 2. I'm running a database of just over 1,000 JPG images that vary in size from a few hundred kilobytes to 5MB each. The Aperture database lives on the SSD, and the images themselves are on the spinning hard disk.
This video would be much more interesting with RAW files, but that's all I have to show, at the moment.
Pretty fast, eh? Also, nothing is cached. I did the video capture after a fresh boot.