April 4, 1975. The Giant was born.
The legendary duo of Bill Gates and Paul Allen started out with their venture called Microsoft. It kept on growing and even made the Goliath a humble creature!
Check the entire history of Microsoft in Wikipedia.
Maybe ISO thought the approval of OOXML standard will be a birthday present for Microsoft! (Here's the pdf)
And the legendary Steve Ballmer joined the team 28 years back, on June 11, 1980. I don't know why, but the number reminds me of the Zombie films 28 Days Later and 28 Weeks Later. Maybe the Open Source Freaks should take a hint from here and make a movie showing the 28 Disastrous Years! Or better, if I get time, I will make one myself!
See what Wired has to say about this. And read more about Zombies here.