Google doesn't have a special holiday logo, aka Doodle. Bing does have a summer-like design but the "hotspots" have no direct mention of Labor Day.
You'd think they forgot it was Labor Day.
Google does have their American flag under the search box, which is something they've been doing for the past few Labor Days. Bing does have a Labor Day themed background but again, the "hotspots" have no direct mention of Labor Day, at least not at this moment.
I probably will keep it light here today but I did decide to follow up on that possible late-August Google update and Google does take off today. So we will see when I get a response to that update.
Forum discussion at Google Web Search Help.