That's correct; it's in the plist file
~/.MacOSX/environment.plist
It contains key-value pairs for any environment variables that might you want to set for the whole login session. Unlike .profile or.cshrc, this file is available to GUI programs. However, you can't use any other programmatic constructs or access other environment variables here, like say, you can't use $HOME. Also, it's no longer supported under OS X 10.8 Mountain Lion.