The MacBook now uses PC3-8500 RAM. Conveniently, all Apple portables with RAM slots as well as the iMacs currently use the same RAM type.
Like the Pro models, the RAM chips are stacked vertically, one directly above the other.
Our machine came with two 1 GB chips. Apple says the machine will support 4 GB maximum. There are 4 GB PC3-8500 chips available, and users have reported successful installations of 8 GB chips in this model.