I ran across this article while trying to find out how many objects are being tracked these days (still haven't found a number for that).

What's interesting is that only two recent events have apparently contributed 40% of the total orbital debris, according to this article. One is the Iridium incident. The other is from when the Chinese destroyed one of their old satellites with an anti-satellite missile in 2007. (But didn't we also shoot down one of our own retired satellites some time later in response? That should be one of the top "polluters," too, you'd think, right?)