That's awesome, didn't know that their friendship was that deep. It's one of the greatest rivalries in the sport, with no doubt.
I guess when it comes to a rivalry, being heralded as one of the greatest in sports ever, to the point where you, Player #1, will always see your name connected with Player #2, who happens to be RIVAL #1 - there´s merely two ways to go from there - either you´ll despise that other
guy forever, or, Alternative #1, you'll manage to appreciate that fellow as only adding to your legacy, and develop some kind of a respecting, friendly relationship.
It's bloody obvious which of the two extremes Federer and Nadal have chosen to follow by now - if you're not a hater of either of the two, it's clear to see for anyone.
These fellows like and respect each other, and rightly so.
This is Navratilova/Evert all over again, rather than Connors/McEnroe and/or Sampras/Agassi, as became mighty obvious lately.
And I love it.