I like to jokingly call google "my external memory". It's fast enough that I can actually use it as such in a IM conversation. When somebody mentions something I'm not familiar with (like a movie) it's usually faster to google it then to wait for them to answer my "what is X?".
A really big thing will be when we'll be able to do the same in a face to face conversation. I really understand why google is trying so hard to be mobile. Otherwise it would miss the next few big revolutions.
Last Christmas we were playing some kind of Jeopardy in my family and of course everyone was trying to use their portable wireless device to cheat one way or another. It's really an acceptably functional "external memory".