Hi Modular, great question. We actually already use Obfuscation in 3 steps, which can be enabled in the BuildSystem service by the Delta Engine user.

Step 1: Your source code will be reduced to the local files needed and stripped of all comments, then compressed and encrypted (see Delta.Utilities.Cryptography and Delta.Utilities.Networking if you are interested)
Step 2: The BuildSystem then strips out all the code that is not needed and reduces the number of assemblies, applies all Build Converter Rules to make your code even run on the target platform. The code looks much different at this point already from what you see in Visual Studio.
Step 3: Finally all of this is given to the obfuscator, which totally mangles everything around and makes the method names, etc. completely useless.

If you don't want all this to happen, you can just disable this feature for your project, but by default it is on and all of our games we have released (we have been doing .NET games for 10 years now) are obfuscated (even all of the engine assemblies are obfuscated as it makes execution faster and assemblies smaller, however that level of obfuscation is just the bare minimum since the engine is open source anyway ^^).

Hope that helps, more information can be found soon (v0.9.0) at: http://DeltaEngine.net/Wiki.WindowsPC

Well, content on the server can be public (visible to anyone), private (only visible to you) or protected (visible to others in a reduced version, but need access to use, good for selling stuff).

You probably mean the content on the client, which won't matter on most target platforms as the content is in some platform specific format and most users of iOS or Android or WP7 won't hack their device just to look at a boring texture ^^

For windows you can choose which modules you want to use (OpenGL, XNA, DirectX 9, 10, 11, etc.) and all content will be processed to run best on those platforms. Currently all the content (FallbackContent) for the engine is NOT processed, it is 1:1 was we put in there, which makes testing easy and allows extending content with ease. Normally you won't see this in games or applications. Take a look at our ZombieParty game (the free version ZombieHockey can be downloaded from our website, also coming as an tutorial game in v0.8.7), there are no simple files you can look at or modify that easily (mostly .rgba4 files are used here). Additionally you can write your own Content Importers/Exporters/Processors to encrypt or pack content in whatever way you like (in the future).

Thanks for the suggestion, added this question to the FAQ, which we have to clean up soon (half of the questions are not even in there and it needs sorting and cleanup ^^).