April Fool's Day is a holiday that is not celebrated everywhere. It's a day of harmless, practical jokes. A day of laughter. It is hard to celebrate online since part of the fun is seeing the reaction on someone's face. And online you can't do things like switch the salt and the sugar (which leads to people putting salt in their morning coffee).
Bloglines ran a nice April 1 press release. The byline clues you into the fact that its a joke (Oakland, CA, Earth -- Stardate: 2005.4.1). Fun to read...but do wish they could see the look on my face.