If there is a leak, a first as far as I know, it will be Kagan or Sotamayor or their staff that does it.
If it’s a negative, ie, strikes down Obamugabecare, it won’t be leaked.
If it’s a positive, ie, upholding it, it will be all over DC before the day is out.................
Maybe the Chief Justice will make an offer to Scalia--"You can write the majority opinion, but only if you read the entire law."
Then no leaks is good leaks.