Numbers game: 75M Mac OS X users, 1M SDK downloads, 50,000 apps

As with most keynote presentations, Apple released a lot of numbers about just how many people are adopting the Mac and iPhone platforms.

First, over the last three years, the active Mac OS X installed base has grown from 25 million users to 75 million users. This is great news for the platform and for the entire Mac ecosystem.

Also, over 5,200 developers from 54 countries around the world are attending WWDC. Over a million people have downloaded the free iPhone SDK, and created 50,000 applications for Apple iPhones and iPod touch devices.

Speaking of which, over 40 million iPhones and iPod touches have been sold to date. In April, Apple announced that those users had downloaded a cumulative total of one billion applications.