Momentous April Days in History
Today our Technology channel has a marvelous series of essays on the meaning of mankind's voyages into space, on this the 50th anniversary of Yuri Gagarin's first flight. They're all interesting, but you can't go wrong by starting with a social/technological history of the famous first "blue marble" shot of Earth from afar, by my old Texas Monthly comrade (and Apollo 13 screenwriter) Al Reinert.
Google is also noting the moment, with this "Doodle" item on its home page:

But what about Clippy? It's a big day for him too. Ten years ago, he was finally given the deep-six at Microsoft, or at least turned off by default as the first step to full elimination, so he would no longer automatically pop up with such helpful observations as, "It looks like you're writing a letter!"

I have long prided myself on playing at least a footsoldier's role in the long and ultimately successful struggle against Clippy during my stint at Microsoft in 1999, as previously recounted here, here, and here. Also see an authoritative analysis of just why Clippy was so annoying -- and, OK, perversely so endearing -- by a friend from my Microsoft days, Chris Pratley. (Summary: it was "optimized for first use," so it was conceivably helpful the very first time you were writing a letter, and increasingly maddening the next zillion times it popped up whenever you typed "Dear Mr. X...") Thanks to Kevin Stevens for the reminder of the date. Somehow I feel a solidarity with the gantry engineers who helped prepare for Yuri Gagarin's launch. We all were part of something larger that moved humanity ahead.