There is a 2GB minimum, but my experience with Lion makes me totally agree. 4GB minimum for standard performance. Even with Snow Leopard, if you can go to a maximum of 8GB then do it. RAM has rarely been as cheap as it is now. My MacBook Pro (Early 2011) palpably sped up when I went to the full 8GB. Mac Pro users should try going above 8GB as the kernel starts to scale the maximum limits of things like processes.
7/15/11 at 1:46am