What's the make-up of the electorate?
How does voting work?
The short version is that as soon as a candidate has two-thirds of the cardinals' support and accepts, the die is cast and he's the pope. John Paul II changed the rules in 1996 to make a simple majority all that's required for papal election (but only after 30 rounds of unsuccessful balloting), but Benedict XVI changed it back. Then again, over two-thirds of the College of Cardinals was appointed by Benedict, and if they hold similar views, that could mean less gridlock.
The longer version is that the cardinals sequester themselves in the Sistine Chapel and take a series of votes until the process is complete. They are expected to take one vote tomorrow evening, and four votes each day after that, two in the morning and two in the afternoon. The ballots are burned after the two morning votes and the two afternoon votes at noon and 7 p.m., respectively, to prevent post-election analysis of cardinals' selections. If a pope is elected in the first vote of the morning or of the afternoon, that vote's ballots will be burned earlier, at 10:30 a.m. or 5:30 p.m., respectively. Giovanni Battista Re, as the oldest cardinal under 80, will preside.
As the ballots are burned, a second stove is used to emit either black smoke (signifying that no pope has been chosen yet) or white smoke (signifying that there is a new pope). Cellphones are banned and plastic sheeting put up around the chapel to prevent onlookers from viewing the proceedings. Jammers are also used to prevent any access to cell or data networks.
Who's in the running to be pope?
*Methodology note: First, I converted each to decimal odds (wherein odds of 2.5 mean I get $2.50 if a $1 pays off), then averaged them (and for Betfair, average the put and lay costs), and then calculated the probability of each papabili implied by those odds (using the formula that the probability = 100/(decimal_odds)%).
Update: The chart has been updated yet again, this time to correct for the house's margin included in the face odds offered by the betting sites. The current numbers should better reflect the papabile's odds.