We bought a couple of Macs last year and have been experiencing 'static' shocks from the iMac's metal keyboard. It is more of a continuous shock though, as if it needs to be earthed. The same applies to the actual CPU/screen's metal surround. This, when touched, vibrates electrically, again as if there is a problem with the earthing wires. We have been using one of those keyboard "zCovers" purchased from the Apple store which helps me but the kids just toss this aside as typing is such a drag with it on.
My MacBook Pro also has that electrical vibration to its metal casing!
We have ceramic tiled flooring, no rugs or carpets and always walk barefoot - we're still 'shocked'.