From the Camera and Imaging Products Association:

PictBridge is "the new industry standard in direct photo printing that enables consumers to connect their digital camera or camcorder directly to a PictBridge-enabled printer..."

See http://www.cipa.jp/english/pictbridge/index.html

Wait... isn't this is what Exif is for? Or am I confusing two different standards (what is the difference, anyway). To a digital photo novice like myself, the printing waters seem to be getting a bit murky with DPOF, Exif, and now PictBridge... or perhaps it's becoming more clear as a result?

DPOF (Digital Print Order format) allows the camera users to select individual image files for printing by photofinishers. Depending on the version (1.0 vs. 1.1) DPOF will allow you to designate number of copies, print size, index print, date/time stamp, cropping and other data. I think DPOF is primarily backed by Kodak, Canon, Fuji and Panasonic.

Exif (Exchangeable Image File) is an image file format sponsored by the Japan Electronic Industry Development Association (JEIDA). Basically it allows the image file to be read by any application that supports the JPEG standard. It also contains data such date/time, exposure, ISO, aperture, shutter speed, and other useful data the photographer might want.

CIPA PictBride is a PTP protocol for USB communication (if I remember hearing correctly, I haven't read much a bout it yet). This will allow any DSC to directly connect to any printer that supports CIPA PictBride, thus bypassing the computer. Right now the direct connect feature between DSC and printer requires specific model cameras and printers to be used.