I have been watching Yahoo's Search Assist and it seems to be getting smarter. So obviously it has some record of what I am searching for during a session (I hope they have not cookied me) and using that to improve their suggestions.
Funny I remember having this conversation with a friend maybe 5 or 6 years ago.
We were discussing how search could become more intuitive. The example my friend used was Albert Einstein. If you want a bio then a straight search would generally list a wikipedia entry or something similar. But what if you wanted his formulas or theories... a search assist to offer deeper suggestions would be appreciated. This is done to a degree by IGoogle and now by Yahoo Search Assist.
But what if you were looking for your local plumber Albert Einstein - now he would be buried amid the millions of pages of the famed scientist.So a more detailed search would be needed and ultimately he would be found. The use of these search histories would help, as would Google Bookmarks.
Christopher Noll from PC World recently wrote a great article on plugins that help improve your browser...
The push to build the browser into a search assistant seems to be an area that is getting a lot of attention right now.... something to keep an eye on.