Preprocessor directives

I know that Unity has at least some preprocessor directives. The only info I’ve found on this is version checks, but are others (in particular, platform-specific defines) available? Or better yet, is there a list of them anywhere?

Searching in the reference yields no results, searching the web points me to a three year old forum post…

http://unity3d.com/support/documentation/Manual/Platform%20Dependent%20Compilation.html