His tongue-in-cheek list includes:

• You get a free pass to conferences by converting your work into presentation
• You get a "trading card" and considered a star
• You can flame the documentations without needing to do anything about it
• You can license your work to forbid any commercial use or further improvements

Hannes also responds in a later comment to the post:

More and more people are thinking about themselves and publish their work on their blog or sell it. There isn't anything wrong with that, but its very annoying that user need to search for information on blogs, commercial websites or magazines rather than the manual.

Here is the evolution graphic for PHP, in August 2006. To learn about the methodology, see la section phpversion. 15 millions servers were surveyed during August, and 8,2 were used for the stats : domaines without web sites, those unreachable, ISP or domain parkings were not considered.

PHP's overall adoption dipped down a bit this month, mostly due to the comination of many other smaller languages rising in popularity. All the while, though, PHP5 adoption is soaring, even gaining back ground it lost last month, and PHP 4.4 is growing more in popularity of the 4.x series versions, almost overtaking 4.3.

The complete stats are available here and the details behind them are here.