Apple does ship 2 socket servers - the Xserve and the Mac Pro is a dual socket system using server xeons and a server chipset (thus fb-dimms).
I'd say they'll either be the first or among the first to ship the mobile and server versions of the chip. Apple doesn't use desktop chips in any model (iMac, Mac Mini use mobile chips) so they don't come into play. Apple pays a premium for these chips by way of not taking co-marketing dollars (thus no Intel jingle in Mac ads). Intel also likes putting their chips in Apple products because Apple is better at marketing than Intel is, and Apple actually makes a bigger deal out of offering Intel's latest and greatest than Dell, HP or the rest.