One of my sites was hit by April's rounds of Panda refreshes. Shortly after being hit, I noticed that no pages of my site were cached by Google. That remains true to this day, but I don't know for how long it's been true.
I launched a total redesign of the site within a few days of being hit by Panda (the timing was coincidental, it was something I'd been working on for awhile).
In your experience, is it common for Google to stop caching pages on pandalized sites? Conversely, is there anything I could have technically changed during the redesign to dissuade Google from caching the pages?