How do I setup Eclipse to work with the newest BlackBerry SDK (I have the new Bold 9900) on my Mac and can the simulator for the Bold 9900 work on mac?
You're out of luck. If I recall correctly they provide a Mac OS installation package (Eclipse+SDK) for OS 6, containing the necessary binaries (precompiler and such), but there is no simulator for Mac OS. You need a physical device.
See http://us.blackberry.com/developers/javaappdev/macosx.jsp
Once you have the OS 6 thing up and running, you can install the OS 5 or 7 SDK.
It occurred to me that the setup application (named BlackBerry_JDE_PluginFull_1.3.0.201102031007-19.zip) I downloaded wouldn't start, which was due to the binary in there not having the correct executable permissions (i.e. 0755) after unzipping.