You're right, the poorly implemented copies of Gmail features could just as easily been written by Xooglers, but it's a funnier and longer-standing joke that the entirety of LinkedIn is as a hodge-podge of other peoples' ideas.

Google and LinkedIn are swapping buildings, so that will no longer be literally true when the swap is done. But I agree that it's a silly thing to say; Silicon Valley companies do swap employees all of the time.