The same user who spotted the supersized Google sitelinks is now saying he is seeing a new feature being tested by Google for voice search on Google.com.
The feature seems to detect if you have a microphone enabled on your computer and if your browser support it. If it does, it adds a "Speak Now" widget to the search bar so you can use Google's voice search feature instead of your keyboard.
He posted a screen shot of the "Speak Now" feature on WebmasterWorld. It looks like this:
The user promises to not be using the Google Chrome extension Voice Search which seems to be doing the same thing. Do I trust him? I think so. He said, "Not using any extensions this just popped up tonight. From what I understand this was only available with mobile devices in the past."
Another user on Twitter said he spotted this as well. @NatoriousFAT said: "I just discovered the microphone button on Google. I'm never typing a search again."
Anyway, it would not surprise me to see this in action on Google as a test.
Forum discussion at WebmasterWorld.