GoogleGuy says the supplemental results are in addition to the regular index. (Personally I still don't understand this - why aren't these pages in the main index to begin with?)
[Link to quote
"Sounds like an excuse for hiving off a chunk of the main index. Is this another pointer to capacity problems and people trying to invent ways round them?"
Hi valeyard, and welcome to WebmasterWorld! The supplemental results are above and beyond the pages that we already search. So we're not taking away any docs--in fact, we're searching even more docs than before.