Vista will include the ability to use USB 2 memory in the context of its "ReadyBoost"
"Windows Vista introduces a new concept in adding memory to a system. Windows ReadyBoost lets users use a removable flash memory device, such as a USB thumb drive, to improve system performance without opening the box. Windows ReadyBoost can improve system performance because it can retrieve data kept on the flash memory more quickly than it can retrieve data kept on the hard disk, decreasing the time you need to wait for your PC to respond. Combined with SuperFetch technology, this can help drive impressive improvements in system responsiveness."
SATA 3.0 gives bandwidth of 300MB/S and USB2 only 60MB/S
Why in the world would I use a USB thumb drive over a modern HD?