What about a webcam attached to some USB storage and a hardware controller that continually records video, storing only the last 30 seconds or so, and attached to a button that saves the buffer for review and Vine upload.
Wireless web interface for API and stuff.
So it would need a camera interface first and foremost.
And storage to save the buffer.
After that, networking to upload to Vine.
A web interface is only necessary for configuration.
Do it on the eeePC first. Then see about a separate unit.