The Google Blog announced that they will be adding personalized search results by default for any person signed in to their Google Account. Read more Here http://www.seroundtable.com/archives/007384.html
I don't like personalized search that much. I think that Google will have to improve on it so that it really becomes worthwile using it. Have you people found it to be better than the normal search???
Hmmm this is interesting especially the way sites rank differently for the same key word in the normal and personalized results. I guess it is another thing that is going to make it harder to optimise for SEO.
Google keeps on making improvements and enhancements with their service. But this enhancement will just complicate searching. I would stick with the old Google search engine. The simple, the better.