It's a sad truth that the primary market for webcams has always been "adult entertainment". This favors cheap devices with optics that leave much to the imagination (example, Microsoft's disappointing LifeCam VX-6000). Bad news then for business users who need a sub $300 desktop solution that will work with a typically stressed corporate LAN/WAN.
Until a year or so ago Mac users had a uniquely only good solution -- the Apple iSight. Firewire, not coincidentally. Even Apple couldn't make money off this market though, and they downgraded to a cheap embedded solution that won't work for sharing whiteboards (newer iMacs have a slightly better camera, but it still doesn't focus).
PC and Mac users alike had another solution -- about 3-5 years ago. Back then Canon (and others?) sold firewire connected digital video cameras with a "network mode"
...You can turn your Optura camcorder into a powerful webcam. Both the Optura 400 camcorder features a Network Mode that enables you to remotely control your camcorder through the DV Messenger2 software application. Control the focus and zoom of your camcorder from a computer while streaming the video via its IEEE 1394 terminal...
Those were the days of good articles on using a camcorder as a webcam and software to fill in what vendors left out. Not any more! I can't find anyone who sells a digital video camera with this kind of capability today.
So, basically, USB and lack of customer interest killed the mid-range high quality PC webcam market, and the Mac market may be little better*. I hope Cringely is right when he says that new teleconferencing solutions are just around the corner. There's nothing to do now but wait ...
*Andrew is going for his iMac soon, so I'll have an update on how well Apple's new embedded webcam works. A used iSight, btw, sells today for about what it sold for brand new.