When adding a new site I suggest the BQ template page contain a META tag telling robots not to index or cache the page.
<META NAME="ROBOTS" CONTENT="NOINDEX, NOFOLLOW">
That will stop this from showing up in the error_log:
[Sat Jun 28 12:55:52 2008] [error] [client 66.249.72.14] File does not exist: /home/.sites/##/site##/vsites/example/web/login
Even though the site wasn't linked from anywhere, Google apparently looked for the domain name somehow and began following links from the main page as I was setting up sub-domains.
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Dan Kriwitsky