I'm looking for a visual diff tool for Mac OS X that will allow me to see differences in Pages (from Apple's iWork suite) and Adobe Illustrator documents. I realize a visual diff may be a little much to ask, so I'd settle for some sort of XML or plain-text comparison. I'm using Pages to maintain my Spec and Illustrator for my mockups, which are all version-controlled, and would love to be able to easily see the differences.
FileMerge (which ships with Xcode) just barfs up gobbledygook, so binary comparisons definitely won't work. I know about Kaleidoscope, which does support diffs on various image formats (and seems to be an all-around good solution), but it doesn't seem that it supports Pages or Illustrator.