Just as subblue (Tom Beddard) ported over the Mathmap Droste Effect filter to Adobe's Pixel Bender Toolkit, maybe we'll benefit from other cross pollinations. According to Chris Parish, Pixel Bender is similar to Apple's Core Image (and so too is Conduit similar to Quartz Composer), and there's parallels not just to Processing, but to Mathmap and Mathematica.
Mathematica 7 added a suite of image processing and video functions to its visualization tools, which are discussed in the blog post The Incredible Convenience of Mathematica Image Processing, and in an introductory screencast and a specific screencast on image processing. Popular items like a lenticular 3D Periodic Table is just the tip of the iceberg -- Slashdot calls it the most expensive clone of Photoshop ever.
Also interesting is The MathMap Composer. MathMap is "a very generic image processing tool in the form of a GIMP plug-in (it can also be used as a command-line tool, though). This newest release sports a very exciting new feature, called “MathMap Composer”, which is similar in spirit to Quartz Composer for MacOS X, or, to pick a more well-known product, Yahoo! Pipes." Here’s a screencast presentation: