We are now going down a slippery road.
I agree that if a site is not using absolute linking then it will cause problems. That said you should use absolute over relative links anyhow.
Google indeed does take relative links to mean on the same site. I had a problem recently where google was getting confused by relative linking and load balanced servers. I can't say too much as it is confidential, but safe to say that thanks to relative links, google got totally confused and completely screwed up the target location, assigning them to a completly different domain name.
My advice is always use absolute links.
I agree with you again though that they need to see the http &/or www. to know it is a link I did say that google would 'pull the url' . ../page.html really isn't a url it is a relative page address.
