Ah - that's what happened to my laptop ...

This is on my shiny new Lenovo T400. Pretty nice on the whole (love the battery-life, light weight, and especially the daylight-readable LED-backlit display, all at a fairly modest price), but it was disturbing to have my Ethernet interface dead - even on Windows. (I needed to run a development system because of the new Intel chipset - otherwise no WiFi and borderline X support.)
I bought a cheap Airlink 101 USB Ethernet Adapter, which worked out-of-the box (even on the older Fedora 9), but it's obviously less convenient than the builtin Ethernet port.

Thanks to LWN, at least I now know what is going on!