HOW-TO: Leverage the power of udev to manage your USB devices.
I've found a very up-to-date, accurate, fairly comprehensive, and well-laid-out guide to using udev for your USB devices. It's on the Gentoo Wiki (naturally), but applies to all distros using a 2.6 kernel, and is completely independent of any desktop environment (such as KDE or Gnome). In fact, if you don't mind getting your hands dirty, this can give you a much more powerful solution than what's built into KDE and Gnome.
This is ideal for USB thumb/pen drives, Palm devices and other PDAs, mice, and even missile launchers!
Here's the link.