Read more at ZDNet.com:
"Google launched an experimental application that can basically be used in as a replacement for Spotlight. Is it better? Well, it does seem speedier to me, but it’s not a huge improvement in that sense — the improvement comes in the quality of search results. Spotlight results do show up in the Quick Search Box results if you want them too, also — that should make people a bit less nervous about trying to use this exclusively.
Currently, it doesn’t search your Gmail account, but don’t expect that feature to be too far down the road once they determine if people like the new application."