Quoting BLuKnight
Actually, if you were to have a flash drive that ran off your MB or the PCI bus, you'd find it much faster than your hard drive. Eventually, you'll have your OS on an internal flash drive (5 to 10 gigs) and all your programs will run off the hard drive. This way, you're running the OS out of memory that doesn't disappear when the entire system is shut off.
I think you're thinking of those RAM drives that have been popping up recently that use DDR as the memory and have a battery backup. Flash is inherently slow to write to due to its nature as EEPROM. EEPROM is not RAM.
-drasnor