Today is Martin Luther King Jr. Day (more over here) and for the special day, we have a special theme live. Here is what it looks like:
Google, DogPile and Ask.com also have themes up. Yahoo and Microsoft's Live seem to not have any logo live at this moment.
Here is Google's logo:
Here is Ask.com's home page:
And here is DogPile:
Forum discussion at Search Engine Roundtable Forums.