I often notice changes in the Google search UI, but the changes happen in such dribs and drabs that I don't think "wow, they've really changed something." Google is now promoting the sum of their latest changes as "Google Universal Search," and the changes do add up to something significantly different that one can point to.

Although these changes all happened a couple weeks ago, I finally got curious enough to see if anyone had reviewed them. Sure enough, I found that Danny Sullivan had two thorough reviews:

• Google 2.0: Google Universal Search
• Google's New Navigational Links: An Illustrated Guide

Both reviews are illustrated with before and after example of the changes in the UI, which makes the reviews especially informative and educational.

The new search results might be looked at as an interesting take on federated search, albeit Google is aggregating search results from its own vertical search indexes (e.g., video search, travel search), rather from fully separate systems.

Also, some of the Google results have something of a best bets quality to them, where you are supposed to feel even more like "they know" what you are looking for, and they are suggesting good options for you. With Google, of course, these suggestions are algorithmically generated rather than compiled by hand.

Coincidentally (or not?), the new Mahalo search engine is built on largely hand-compiled best bets. And, they are seeking to differentiate themselves from Google by focusing on hand-compiled / hand-edited search results rather than purely computer-generated results.