Today is Independence Day in the United States Of America, the 238th birthday of USA. To celebrate, Google, Bing, Ask.com, Dogpile and others have special logos or themes on their home page. But surprisingly, Yahoo did not animated their logo - not yet - at least.
Google's logo is a video but also an animated GIF. It first loads an animated GIF and when you click on it, it loads a video powered by YouTube.
Here is the animated GIF:
Here is the video:
Bing's home page:
Search Engine Roundtable:
Forum discussion at Google Web Search Help.