I've been toying with getting the Kingspec SSD for my MacBook Air, as the first gen requires a ZIF PATA connection, and 1.8" seize, and they're really the only ones who make one (OWC has an option but it's more than double the price). Being limited to 2GB of RAM, I think it'd benefit from an SSD.

I'd actually be kind of interested in doing this on my clamshell, the old IBM hard drive is a bit noisy. Too bad getting those apart is a pain.

I don't think I would see a benefit on my 12" PowerBook though.