Though not yet supported on OSX, this (or a product like it) could help assuage the angry Apple hoard, upset over Apple's decision to nix FireWire from the latest MacBooks. You guessed it...you'll have to buy it, even if it does happen, and don't expect true FireWire sustained speeds either.
Apple’s decision to axe FireWire from the MacBook line is not sitting well with many users, to say the least. For high-quality audio and video transfers, FireWire is the standard for professionals and hobbyists alike. Though USB is technically capable of faster transfer speeds than FireWire 400 (480 Mb/s vs. 400), FireWire has greater effective speed and power distribution because it doesn’t depend on a computer host port.