there's an app floating around that will let you use an sd card as a swap partition, but given that your internal drive is also flash memory, why wouldn't you just increase the size of your swap partition on the internal drive? or am i missing something? that's not a "readyboost", it's just a virtual page. meh.

i mean, it could be useful if you're in a pinch. but, it's not a replacement for real ram.