Chrome seems to have been the first to start hiding the http:// prefix last year, and there seemed to be significant contention. Rather than show the full prefix chrome lops off http:// and displays the "meaningful" part of the URL to the user. Here are examples from the latest Chrome and Firefox, contrasted with IE8 which does not remove the prefix:
A lot of the reasoning against removing the bar seemed to be questions of implimentation: How would users know they're on https/ftp protocols, and what would happen when I copy an address with no http://? Chrome and firefox solve the first by showing all non-http:// protocols (as they're the vast minority of cases) like this:
Chrome and firefox also add the http:// prefix when you copy the URL, so when pasting it to send to another user the link they send is sent in full. Popular sites like Twitter and Stack Exchange have begun to hide the prefix when posting URLs as well as they're not needed.
It seems to me the http:// prefix is excess technobabble for the normal user; for years we've suffered through radio and TV ads telling us to visit h-t-t-p-colon-backslash-backslash-website name... (even though they're slashes). Even the creator of http contends the double slash is a pain in the butt.
Almost all web interaction in-browser is now done though http://, the ftp/ect protocols are almost completely transparent to the end user, usually done through a nice front end that hides the protocols. Is there any good reason to display the prefix anymore? Which popular applications still do make it a point to always include the http:// and why?