今天看赖总的博客觉得很奇怪呢，原来Google Reader的RSS源是区分大小写的

wikipedia的URL页面解释到：

The domain name portion of a URL is case-insensitive since the DNS ignores case. http://en.example.org/ and HTTP://EN.EXAMPLE.ORG/ both open the same page.

The path is used to specify and perhaps find the resource requested. It is case-sensitive, though it may be treated as case-insensitive by some servers, especially those based on Microsoft Windows. If the server is case sensitive and http://en.example.org/wiki/URL is correct, http://en.example.org/WIKI/URL/ or http://en.example.org/wiki/url/ will display an HTTP 404 error page, unless these URLs point to valid resources themselves.