You can plug all sorts of USB devices into your PS3. For example, you can plug in a keyboard and mouse into the system, making your PS3 a rather capable internet browsing device. Binaryfiend from YouTube discovered that you can also plug in a USB tablet, and the PS3 will accept the connection no questions asked. Watch as he quickly surfs through the XMB faster than a standard controller, and see how comfortably he can use the PS3 with just a stylus.
PS3's ability to interface with a variety of non-proprietary devices is really amazing. Add this to the growing list of gadgets we can connect to our systems: keyboards, mice, printers.