It's not the Mac that has the issues, per se, but the software. You need to check the software you want to use with your specific camera and see if RAW is supported by the software that you will use on your Mac. If that makes sense.
For example Aperture 3, which of course is an Apple product and only works on Apple computers, does not yet support the E-PL1 RAW files. It certainly works fine with JPEG, but not RAW. It does work for the E-P2 and E-P1 and will eventually for the E-PL1 but not yet... Check out this link:
Aperture 3 RAW support
I can't speak about Lightroom.
So check out the software you'd like to use for your camera and see if it has RAW support, if that is important to you.