I thought this was an interesting question to ask people because I think it’s often misunderstood. Google treats content found at different URLs as if it is different content, even though it might be the same, such as in the following examples:
http://www.example.com https://www.example.com http://example.com http://example.com/index.htm http://example.com/Index.htm http://example.com/default.asp
One of the most interesting papers I’ve come across on this topic is this one (One of the authors joined Google shortly after this was released – Ziv Bar-Yossef):
Do Not Crawl in the DUST: Different URLs with Similar Text
What do you think?