URLs are case-sensitive, but on most sites they probably shouldn't be. For example, /users/Ben should work as well as /users/ben. This is true even if you have canonical links on your own site, because other sites may link them wrong, or a user will manually type in /users/Ben because he normally types his name capitalized.
Well, it's easy to just return the same page for /users/ben and /users/Ben, but is that the best thing to do? Or is a 301 redirect the better way? (So that users, including Google, never see the non-canonical URL.)
I would use redirects, the reason is that search engines will catalog the different URLs as separate destinations and thus lower your pagerank for that page, along with their positions in search results. Its best to have only one accessible url per destination.
Well, it's easy to just return the same page for /users/ben and /users/Ben, but is that the best thing to do? Or is a 301 redirect the better way? (So that users, including Google, never see the non-canonical URL.)
I notice reddit uses a 301 redirect for the likes of http://reddit.com/user/BenHoyt -- but some other sites just show the page anyway, like http://www.trademe.co.nz/ART/InDeX.HtM -- and still other sites are simply case-sensitive: http://images.google.com/ImageS