If you're even remotely interested in the world cup then my Rugby World Cup Forecast is a great way of keeping up-to-date with how things are progressing.
I don't claim to know anything about the game, in fact there are very few people who know less than me. My forecast is largely based on world rankings but with some additional parameters to take into account recent trends, current performance and performance during the World Cup itself.
The main purpose of the Forecast is really just an excerise in modelling. It isn't intended as a serious attempt to predict the outcome of the world cup. That said, unexpected results like a poorly rated team beating a highly rated one, will have an effect on the expectations for the latter games. That has already been seen with the shick defeat of France in the opening game. The Forecast was initially showing an 'All Blacks' v. France final, but not after that game.