Andylew - 8:26 pm on May 31, 2010 (gmt 0)
What we have found is that a vast number of our pages (that used to rank and get traffic) have disappeared from the index altogether, leaving secondary related pages which rank much much lower (e.g. long article with 10 pages, page 1 disappears, leaving page 8 appearing in SERPS on page 20).
Exactly what we have experienced (on may 1st) pages (around 90%) havent dropped rank they are no longer listed. We await their relisting as by googles own admission the algo update doesnt effect listing (although they could, and do, quite happily drop and relist everything if they wish at any time)