Nexus One owners should receive an over-the-air update soon that brings multitouch gestures, a better Maps app and improved 3G connectivity. "Soon" is relative, though. If you're tired of waiting, a five-minute, legitimate procedure can update your phone right now.
The folks at Phandroid lay out the basic procedure for flashing an Android update package on your phone. The package comes straight from Google, and this method doesn't "root" or otherwise modify your phone firmware, except to drop the good stuff into it.
You'll need a USB cable to transfer the downloaded (and renamed) ZIP package to your phone, and simply reboot your phone while holding down the trackball. At the bootloader screen that pops up, select "Recovery", and then hold down the power button and hit the volume button up — in that order, not together. Your phone will load the update package, ask you to reboot, and you're on your way. Thanks for the link and button-push tip, Joe!