Wouldn't it be easier and cleaner to just keep the private parts in a git submodule?

You can have a look at the TOC here: http://www.amazon.com/dp/B00AGOLLVC ("Click to LOOK INSIDE!")

Why are people getting so excited about realtime global illumination and code hot-swap? CryEngine 3 already supports both, and has done so for the past year or so.

Realtime global illumination has been possible for the past few years. I believe Crytek was the first studio to make a game engine with support for the same (www6.incrysis.com/Light_Propagation_Volumes.pdf)

And the code hot-swap feature in the freely-available CryEngine 3 SDK isn't just for Lua, there's the CryMono project which adds support for hot-swapping C# scripts.

It's a fake article, don't get your knickers up in a bunch.