Apple is just one of quite a few big tech companies signed on to help support the Worldwide Web Consortium (known as the W3C) in developing a brand new web standards resource called WebPlatform.org. The new site is simply designed to get all available information about how to code for the various web standards out there (from HTML and CSS to newer tech like the Canvas API and various Audio plugins) all together in one clean, easy-to-find place.
If you do coding for the web, the site is probably a valuable resource already, and all of the companies involved are trying to convince content creators to help them grow it by contributing to the forums, docs and tutorials currently available on the site.
Apple's got lots of reason to support a movement like this, especially as its various Macs and iDevices claim more and more of the web's browsing audience. So it's no surprise that Cupertino is contributing to make a resource like this available.