To see how it works, you can watch a screencast (13:23) introducing the new search engine here.
You can also watch Wolfram Alpha go live today in a webcast starting at 8 pm EDT / 7 pm CDT / 6 pm MDT / 5 pm PDT. Watch a video (5:04) about that here.
I am pretty impressed by what I saw on the screencast. Generally, I am not easily impressed.
It's going to be fun to play with, for sure. And useful, too.