tangor - 6:20 am on Nov 10, 2010 (gmt 0)
The link I posted reveals this cache behavior:
Within this preview, relevant text may be highlighted and magnified. If you then hover your cursor over any other search result, you can preview those as well.
Dang difficult to do with a graphic image... there must be a content based result somewhere in Google's system... and they are not using it as "cache" but as keep the visitor on Google's site as long as possible.
I'm not liking it...