diberry - 9:41 pm on May 26, 2013 (gmt 0)
That's a very good and precise question to look at, diberry. From an initial check, I'd say #X is not the same number from query to query, but something like this pattern seems to exist for the more competitive transactional keywords - and not for informational queries.
Thank you, Tedster, that's exactly what I'm seeing, except I am seeing it on informational queries. In fact, I just realized I'm seeing it most consistently on queries that use one of the words Google uses as a link at the top of the SERPs (starts out "Web, Images, Maps..."). So it's possible that only informational queries relating to those terms, which Google must index a bit differently, are getting this treatment. I'll have to look into this more.