what modern network scanner can't do that? (I'm serious.)

For a dedicated scanner, a lot of people seem to like the Fujitsu models, though I think my friends are talking about the usb models (s1500 or s1500m?) but you can share them on your network in win7 or whatever I suppose. They have a network version also. Worth checking out.

I have an older Brother MFC-7840W (wireless version) all in one that does that too, and seamlessly on the mac and pc. The mac side auto-detects it and installs the drivers, and includes scan to image, tif or pdf, I believe (selectable dpi, color/b&w, flatbed/sheet-feeder, etc.) On the PC side, you have to install their software package. The scan buttons on the device itself I think are setup to send to one computer, but it's all programmable, I believe. The scan button is programmable to some degree, but I think it supports scan to one computer by default. Not an issue if you use the computer interface, any computer on the network with the drivers can control it.

-David