When it comes to Roland Garros it means nothing unless Nadal draws Djokovic it really means nothing except for whoever of Federer, Ferrer, or Murray draws Nadal in the quarters and is a certain loser and out of the event. Nadal vs Djokovic could go either way at this point probably though, and could take something out of the winner as well. If Nadal feels fit enough to play, and played well enough to be in the quarters, no way he is losing to any of Federer, Ferrer, or Murray at Roland Garros.
Wimbledon is more intriguing. Nobody knows how a Nadal-Federer, Nadal-Murray, or Nadal-Djokovic match on grass would go at this point. Nadal would just be replacing Ferrer (likely out in the 3rd round or so) as the top 4 seed there if he winds up in his quarter.