Q: Can I move my saved regions between Macs?
A: Yes! The App Store release stores region files in User/Library/Containers/com.aspyr.simcity4.appstore/Data/Documents.
OSX 10.7-10.9 now hides this directory, so please press cmd+shift+G to bring up a search window in Finder and type in '~/library' to access this directory.
However, please be advised that any downloaded content from the internet is not supported for this version.