USB 2.0 Now
While it can be agreed upon that Firewire is superior to USB 2.0, it should also be agreed upon that USB 2.0 is a more established technology. USB 2.0 external hard drives, CD and DVD burners, optical drives, printers, scanners, hubs, etc are everywhere. There's even USB 2.0 external sound cards and cable modems. A brief search of PriceWatch.com for "usb 2.0 drives" shows 38 pages of matches at 15 results per page (570 results) - a search for "USB 2.0" yielded 258 pages (3870 results)A search for "firewire drives" shows 35 pages at 15 results a page (525 results) - a search for "Firewire" gave me 114 pages (1710 results).
The reason is simple: nearly every PC sold now and during the past year (at least) has at least one USB 2.0 port (on average four), yet only a minority of those same machines have a Firewire port of any kind (Sony is an exception). Perhaps Firewire 800 will be a little more ubitiqous, but currently USB 2.0's widespread use is why it gets incorporated into most devices.
The battle of a more superior technology over a more common one is nothing new (think Betamax vs. VHS). Firewire has held its own by dominating the niches its superiority really shines through - external storage, video. Firewire will continue to do so in these areas and will most likely expand.
However, USB 2.0 will be with us for awhile. Too many people are using it and creating products that use it. As pointed out in other posts, USB 1.1 is enough for a lot of "cosnumer" applications - external floppy drives, joysticks, ink-jet printers. USB 2.0 is good for more "pro" uses - high-speed laser printing, CD/DVD/Optical external devices that cannot read faster than 400 mbps. I wouldn't be suprised if Firewire 800 started pushing USB 2.0 out of cable modems, high-end digital cameras and external sound cards though.
The point of my rather long and convuluted message is: USB 2.0 has its place. To ensure that Apple computers work with literary thousands of devices that use USB 2.0 at optimal speeds, Apple should incorporate USB 2.0 into their systems. It is ridiculous to think that if you spend $3200 on a top of the line Power Mac you cannot use a widely adopted standard that is support by many products without first buying an $8 controller card.
I encourage anyone who agrees with me to write Apple (
http://www.apple.com/contact/feedback.html) and tell them why APple needs to add USB 2.0 to their next hardware revisions. Share your stories of trying to get PC users to switch who balk at the fact that Apple does not support USB 2.0 Tell them about all the devices you cannot use at advertised speeds because your Mac connects to them via USB 1.1 and not 2.0