tedster - 5:37 am on Mar 21, 2011 (gmt 0)
It means you should check for duplicate URL problems, potentially infinite dynamic URLs that create a spider trap for crawling, and things like that.
For example, if your site has many different kinds of "sorts" and each one assigns a parameter in the query string that makes crawling and indexing your content problematic. Even more, if you assign user tracking parameters in the query string, then every crawl will create a new URL for every page.
Usually this kind of message is only generated if each of the URLs gogolebot is finding do not have unique content - so it is good to understand what is happening on your site and address it as best you can. Your truly unique content will be indexed better and rank better if you do.