Like last year, Google, Yahoo and Ask.com do not have special logos up for Labor Day. But Dogpile and even Live.com have logos or themes live for the day.
Here is DogPile's logo:
Live.com has a mention of Labor Day in one of their mouse over elements:
We at the Search Engine Roundtable have a theme for Labor Day:
It is not uncommon for Google and Yahoo not to have logos for Labor Day. They didn't have them ever before, we documented it in 2007, 2005 and 2004. Memorial Day is also a day Google won't display a logo, this year, they told us:
Thank you for your note. We understand your interest in seeing a Memorial Day Google logo. If we were to commemorate this holiday, we'd want to express reverence; however, as Google's special logos tend to be lighthearted in nature, this would be a particularly challenging design.
We wouldn't want to create a graphic that could be interpreted as disrespectful in any way.
We have a long list of holidays that we'd like to celebrate in the future. We have to balance this rotating calendar with the need to maintain the consistency of the Google homepage. We really appreciate your feedback regarding the Google logo, and please be assured that we're actively pursuing ways in which we can acknowledge Memorial Day and other such occasions in the future.
The Google Team
American's, enjoy the day!
Forum discussion at Search Engine Roundtable Forums.