Just a quick thought.
Throughout this series Australia have taken their second wicket inside the first 12 overs every single match. They have been exceptional at taking the top off their opposition. Only twice (vs Canada and Pakistan) did the third wicket fall after the 15th over.
India have had great success with their top 3. They have also had great performances from Yuvraj Singh. But Dhoni, Raina and Pathan have all had tournaments to forget so far.
I would suggest that the crunch point in this game will be the first 10 overs of India's innings. If Australia manage to break through early, the pressure may be too much for the Indian middle order to handle.
If they don't break through early, then their plans will all turn to custard very quickly. (for those unfamiliar with this Kiwi expression, despite custard being good, things turning to custard is bad. Especially if it is things like bridges and buildings.)
The other key point may well be the toss. Both teams are bat first teams, and are not nearly as comfortable chasing as defending.