I've just done a clean install of XCode 3.2.6 on Snow Leopard, to the default /Developer dir.
Is the right/normal way that all libs, and software tools such as CMake/git should be installed inside /Developer too? Is it comparable with how Linux expects standard dirs to be used for things, or more like Windows where it's all down to personal preference?
Any good guide for a experienced developer who's a noob to Mac dev is appreciated. For instance I'm confused where and how my SVN client came from and why I have SVN but not Git.
In general, you should not install anything inside of /Developer (not /Development). You should assume that anything under it is managed by Apple via Xcode packages. For additional command line tools and libraries, one standard Unix-y practice is to install them in /usr/local which is provided for such purposes. (Do not install anything in any other /usr locations as they are also managed by Apple.) But, rather than building and installing a lot of third-party software - like git - yourself or using binary installers from different providers which may not play well together, it is a good idea to use one of the open-source package managers for OS X. The most widely used are Homebrew, MacPorts, and Fink. Pick one and stick to it.
In Xcode 3, Apple shipped svn but not git. That changes in Xcode 4, the default on 10.7 Lion, which does include git. And, as of Xcode 4.3, there no longer is a /Developer directory as Xcode itself is now an app in /Applications and the items formerly in /Developer are included within its app bundle.