Link is from Blendernation, but most of the stuff seen here can be done in 2.5 using the internal renderer if you leave out caustics and true GI. (realistic scenes using blurred reflections are now more possible to do with Jaguarandi’s work.)
I’m actually surprised that they didn’t have an example of gamma correction. And it is interesting to note that all the examples of bad CG they talk about at the very beginning was pretty much the only stuff possible when I started Blender at version 2.33 because arealight shadows and AO was real slow.
As for adhering to those rules, I personally think you can fudge it just a little if you’re going after artistic merit, but not if you’re strictly after realism.