penders - 10:53 am on Nov 1, 2011 (gmt 0)
Searching for it returns no results either, so it's not the white on white trick.
Search in-page I assume? If you search Google for a snippet of that text, does Google find it? ie. Has Google actually indexed that text? (Just curious.)
However, if it is permanently hidden from the user and possibly spammy and hence purely for SEO then it is possibly blackhat and they are treading a very fine.