For I, a search engine optimizing dude, it leaves me a bit numb as I consider buzz as :
a. another social networking platform to worry about.
b. another way for Google to track behavior.
This whole discussion is precluded however by Google's changes over the past month or so.
Personalized search is when Google feeds you search results based on your past behavior. So that you will get the sites you visit the most as your top results for a search query.
This is goofy to me since I use Google to find new URLS not old.
As stated Buzz comes with privacy issues since you are actually signed into Google Mail to use it. Google has taken some steps to back off of some of their intrusions one of which was a ready made circle of friends.
It will be interesting if folks really accept the Big G as nothing more than a tool for the geekey. For those multi task social broadcasters Ping.fm has already added Google Buzz.