netmeg - 4:38 pm on Aug 2, 2010 (gmt 0)
My pages in the site: command are listed with no discernible pattern, as mentioned by tedster. (This is easily checked with the SEO Info FF plugin) My home page is on top (unless I've done something stupid - which has happened) and the next one could be a PR0, or a PR4, and I've found PR3s and PR4s on page 4 or 5 of the results.
So I use it to remove urls, check snippets, find mistakes. But I don't put any particular trust in it.
I'm pretty sure Google wants it that way, too.