Apple has announced that the 100 millionth iPod has been sold, slightly more than six five and a half years after it was launched (in October 2001).
Here we've knocked together a graph showing how the total sales have grown, based on Apple's publicly released figures. (You'll probably find just as good a version at its Wikipedia page soon.) (Revised to show sales and totals on different y-axes.)
What does it show? Not a huge amount, though it seems that iPods have been selling just as well since Christmas as during, since to hit the 100m mark now, Apple must have added 11.2m sales since its last announcement - which was of 21m sold in the past quarter. The real takeoff in sales happened in Christmas 2004 - comparatively recently.
Apple's just finished a quarter (ended March 31), so that'll be why it's chosen to tout this number now. Well, now we can all ask two questions: how long will it take to sell the next 100 million; and will the iPhone be included in the totals, and will it slow down the iPod's sales growth rate? OK, that's three questions.