I don't think in Google's history, at least that I can remember, has Google ever posted a Doodle, a Google logo, for Labor Day. They have posted small American flags but nothing more. Even dating back to 2004 and 2005, Google didn't post a Labor Day logo.
That all changed today with this Doodle. Google didn't comment or add any details around who made the Doodle, but it is indeed live. Which to me was a bit of a shock.
Bing normally does something with their background for Labor Day and they did so this year as well:
Here is Dogpile:
So yay for Google for making a Labor Day doodle today.
Forum discussion at Google+.