Firefox 7 introduced a controversial idea of omitting http:// protocol prefix from the URL bar (other prefixes such as https:// or ftp:// aren't omitted). This is very irritating for me personally and I see it as an inconsistent approach which falls into a general modern trend of oversimplification.
Fortunately, it's possible to disable this behavior by setting the following key in about:config to false:
browser.urlbar.trimURLs
Enjoy the full URL again.
