They've been saying that iPhones, iMac's, macbooks etc will work seamlessly together for years though.
I'm quite interested to see how their ARM processor works in a MacBook form factor though ; since moving to Linux....ooh, to many years ago, ARM had always interested me, but it's not quite had the raw shove to do a full, high performance desktop replacement quite yet.
Given how Apples ARM chips have always been pretty advanced, it might start an arms race among the ARM vendors to start getting up for higher power processors.
Ultimately, that leads to more competition and that's a good thing for everyone.
So while I normally don't care for WWDC, as a tech nerd this one has got my attention.