eljefe3 - 5:51 am on Jun 6, 2002 (gmt 0)
I would put in a robots.txt to keep spiders from accessing the information if it is very similar. However if the content is different than there should be no need as the content will not look like spam. If there is some overlap on content that is fine. If the content is more than 50% redundant between the subdomains and the main domain, than a robots txt might be needed.