Face detection is possible in webOS [OSCON2010] 24
Theoretically, anyway. I just caught a great session covering facial recognition on the iPhone here at OSCON by Alasdair Allen (the author of several O'Reilly titles) that delved into technology such as OpenCV and the in-depth coding methodology behind getting the camera in the iPhone to recognize and distinguish human faces. The technology actually works in a similar fashion to how the human eye detects and differentiates faces: the shadows generated by elevation of the physical features of our face, instead of the features themselves.
Since Palm's PDK allows iPhone developers to port their applications over webOS, and after a brief chat with Alasdiar after his presentation, it appears to be at least theoretically possible that an enterprising developer could utilize the methodology laid out in Allen's presentation and upcoming book and implement face recognition in webOS.
The applications of this technology are vast: Imagine being able to walk into a room, snap a picture of your friends, and have your friends automatically tagged in Facebook for instance. What applications could you see?