Reports are coming from WebmasterWorld that when you conduct a country specific search, you are no longer able to see which pages are supplemental.
The example given was a search at google.co.uk. When you conduct a site: specific search for "the web," you would be able to see pages in the supplemental index. But when you refined that search by "pages from the UK," you would not be able to see such results.
We all know that Google hide the supplemental tag from us. I suspect in this case, people are defining supplemental as pages found after clicking on the message that reads:
In order to show you the most relevant results, we have omitted some entries very similar to the ### already displayed.
If you like, you can repeat the search with the omitted results included.
So in short, I believe that message above is no longer being displayed for site command searches limited to "pages from the UK." I tested a few examples, and all have shown that to be the case.
Forum discussion at WebmasterWorld.