I was out at the store yesterday and saw this puppy. Bought one on the spot.
It's a Logitech V450 Nano cordless mouse for laptops. Check out that teensy little USB receiver! Here's how it looks in my laptop:
The "nano receiver" is small enough to stick into the port and just leave there, and it definitely doesn't get in the way of mousing around right next to the machine, either. If you do decide to remove the receiver for travel, it slots into a storage compartment next to the batteries:
Putting the receiver into that slot automatically turns the mouse off to save battery life.
The mouse itself is great, too—a near-perfect copy of the hump-backed shape of the seminal Microsoft Optical Notebook Mouse, the first portable mouse whose shape didn't cramp my hands. I've worn out my MS mouse through years of use, and this is a perfect replacement that practically erases my concern over the fact my laptop doesn't have Bluetooth. Smart.