Macbook Pro 6.2, i5 2.4Ghz CPU, 4GB RAM, GT 330M 256MB graphics, Bootcamp with Win7 64-bit.. runs perfectly. Had to generally leave settings at Medium, but have full shadows enabled, and it's pretty fluid. No crashes in Beta after about 20hrs playing.
The mac will run HOT though (especially around the power plug/video out port/back-left), make sure you sit it on a laptop raiser with good fans.
Incidentally, loving Rift!!