The last time Ferrari had two world champions was in 1954 with Nino Farina and Alberto Ascari.
The surprising thing in Kimi hiring by Ferrari now 2013, was the way he left the team in 2010, which at the time was preparing to receive Alonso. With contract still running Kimi was discharged and stayed receiving salary throughout 2010 even without driving.
In addition some disagreements with the team direction caused some strangeness in the last months of the relationship as Raikkonen never bothered much with the extra-track appointments, as interviews with the international press and events with sponsors. When his departure was given, the own team internally have questioned its uneven performance, very different from when he became champion.