What is Mindset? A new twist on search that uses machine learning technology to give you a choice: View Yahoo! Search results sorted according to whether they are more commercial or more informational (i.e., from academic, non-commercial, or research-oriented sources).

Link

Some tests already performed with its relevancy

• Test 1
• Test 2 - Rusty Brick

My quick question:

If you do a query like site:www.sitename.com, on a blog that has the same type of content why you get different results

But a promising demo after all. I want to see it integrated in the official search

Good job Yahoo

Edit:

Here you have an interesting test. I laughed a lot while looking at Microsoft results