Some of my most viewed things on Flickr are Processing sketches:
http://flickr.com/photos/tom-carden/tags/processing
Jared Tarbell has some stuff on Flickr too, e.g.
http://flickr.com/photos/generated/tags/computation/
http://flickr.com/photos/generated/tags/computational/
http://flickr.com/photos/generated/tags/complexification/
I agree it's a nice place to put things as you're working.
That said, I think that the Flickr people might not be so accomodating. Because they like to encourage a 'photos only' attitude to Flickr, they will probably ask you to mark your images as 'may offend'.
This seems odd but it takes them out of the public areas (especially tag pages) and means that people looking for photos are less likely to be annoyed by them. They ask the same thing of people posting screen shots or lots of CG. If you don't do it they just mark your whole account that way when they notice you, and then none of your photos will show up in public areas
That would mean that a 'processing.org' tag was next to useless, however, and we'd be stuck with only using a group.
Maybe we could make a tool for the Processing IDE which would post a screen shot to Flickr and automatically mark it 'may offend'* and post it to a Processing group though?
'may offend' means NIPSA/Not In Public Site Areas, I think. http://flickr.com/forums/help/14692/#reply74559 has the current Flickr line on this