Well it appears as if all the ‘don’t worry about your pages being in the Supplemental index, it will not hurt them’ message that google has been sending out, no longer applies.
Try this test for yourselfCarry out a site search, and find a page in the supplemental index (they are clearly marked in green text as supplemental). Now visit that page, and grab a chunk of text.
Take that chunk of text and do a phrased search for it in Google ” your text” I will bet you that the page does not show up. So the reality now is that if your pages are supplemental, then they just as well not exist as far as google is concerned.
This now puts a whole new complex on how people look at Google. Why plough £££ or $$$ into Adwords when they will not accept into their index pages that they feel are not of a good enough quality, YET they are happy to send visitors to them if you pay!
Time for those with Suplemental pages to start looking at alternative PPC providers I would say. EITHER your pages should be good enough for Google to send people to or they should not.