Evan Williams is one of the founders of Twitter. He also co-founded Pyra Labs, the creator of Blogger.
He listed five reasons why domains are getting less important.
There was as time when you knew your friend's and family member's phone numbers. There may have been a time when you knew the addresses of people you emailed a lot. And there was a time when I knew how to get across town without using my navigator. Software has taken over these jobs from our brains, because it's better at it. Domain names are like phone numbers and email addresses—unique identifies that allow computers to disambiguate from the more natural (but likely non-unique) handles our brains like. (Put aside that domain names are actually the human readable system for IP addresses. They're still computery.)
If you start typing "bob" into the To: field in your email client, it will give you some choices of the Bob's you've emailed before, which is almost always good guess. If it's wrong, you go look up the address and then probably copy+paste it in without really paying attention to what it is.
A lot of people use Google this same way. The first time how saw how often people got to Yahoo by typing yahoo.com into Google, I was shocked. And as this famous comment thread shows—where thousands of Facebook users showed up to a blog post talking about Facebook logins and got confused because typing "facebook login" into Google was how they got there—Google is how normal people get around the web. This probably wouldn't be true if Google wasn't so damn fast. But it is. It's the auto-complete of the web. Well, one of them…
Read the other four here: http://evhead.com/2011/06/five-reasons-domains-are-less-important.html