http://www.gamespot.com/articles/unreal-engine-4-now-free-for-everyone/1100-6425627/
So many great Dev tools are free or cheap these days it's so much fun playing around with these.
I spoke about this somewhere else but, from what I remember reading, the engine was always planned to be free, similar to the model UDK3 was. Originally during development another well known engine went revenue based to sub only based(Hero Engine) so during the beta of UDK4, they determined they would test the water to see the turn out. But had always stated they still planned on the revenue model. So the article is a bit misleading I think.