I first heard of processing , from a post on Natures Nacent blog in which Euan Addie talked of how terrible visualization tools in the bio-space are.
I heard Ben Frys talk at the Ignite Boston event where he introduced processing to the audience and also gave a breathtaking demo ( despite the contrast issues that the venue had) of the app. Especially amazing was his visualization of the HapMap data ( including one that was featured on Nature Magazines cover).
Ben is writing a book for oreilly called Visualizing data ( available through Oreilly rough cut) . I plan to start playing with processing and definitely recommend checking this space for the video link to his talk which should soon be up.
Image: The Processing book written by Casey Reas and Ben Fry