I did a search a moment ago and was surprised to discover that real-time searching is enabled for my account. This is apparently Google's big announcement today. It's kind of neat; no more hitting "Enter" or clicking "Search".
It doesn't seem to be active for everyone yet. I pulled up a different browser without logging in to my Google account and there was no real-time searching there.
The name they're using is "Instant Search" there's an option next to the search box to turn off instant search: