[AznHisoka]

Use Mac Leopard, and don't switch from 32 bit to 64 bit - you're gonna get a massive headache getting all those gems you need to install. Also if you're considering doing anything to do with image processing, consider NOT using Mac. Installing stuff like PIL and ImageMagick can be hell

[james-fend]

Using MacPorts to install ImageMagick was hell. But when I used HomeBrew, it was like night and day.

[rimantas]

I am using Lion and had zero problems with gems.