Extract from Law Clarification 2 - 2011:
There is a further variable to be taken into account when the ball goes to ground at a collapsed maul and there are players from both sides on their feet bound over the ball so that Law 16 – Ruck becomes applicable.
17.5 Successful end to a maul
the ball is on the ground
We agree that the maul is successfully over, therefore the Law Clarification is irrelevant because we have reached the conclusion that the maul is not collapsed.
The question is: at what point is the ruck formed?
[LAWS]16.1 FORMING A RUCK
(a) Where can a ruck take place. A ruck can take place only in the field of play.
(b) How can a ruck form. Players are on their feet. At least one player must be in physical
contact with an opponent. The ball must be on the ground. If the ball is off the ground for
any reason, the ruck is not formed.[/LAWS]
This suggests to me that the ruck is formed the immediately when that maul become over - am I missing something???