Both Firewire and USB have made leaps and bounds in advancements over the years, and as speeds have boosted they have become ideal for plugging in additional storage to machines. IDE and SATA still completely trounce them in terms of actual performance, though. To compensate, USB 3.0 promises much greater speeds than the current generation and now so does Firewire.
The new iteration of Firewire, called S3200, will support speeds theoretically as high as 3.2Gb/s, four times faster than the current 800Mb/s maximum speed Firewire supports. That's a significant speed boost, one that would make the standard very attractive for snap-in storage solutions. USB 3.0, however, promises speeds even higher – up to 4.7Gb/s. But as we've seen in the past, the actual maximum speeds of these buses are rarely achieved. It will be no surprise if the two end up becoming neck and neck, though it's exciting in any case.