There's been conjecture about this subject since Green Eagle raised it on WPW about 10 days ago. It seems I have, what could be termed, almost conclusive proof.
My search blog
http://uksearch.blogspot has just received a visit in response to the search term "Novatex Texas" on Google.com. I recall, earlier this year, agreeing a reciprocal link with "Texas Jeff" a fellow WPW forum member. When I checked the Google search I was astounded to find my site was ranked number 1 in the Google SERPs. See:
http://www.google.com/search?hl=en&q=novatex%20texas
The only connection my blog has with the search term is the outbound link. My blog is only PR4 and has no other connection to Texas or Novatex. Certainly no IBLs. This single outbound lik must be competing with hundreds of IBLs.