Don't know how reliable this info is but according to this source:
Pope Benedict, Joseph Ratzinger, has scheduled a meeting with Italian President Giorgio Napolitano for Saturday, February 23 to discuss securing protection and immunity from prosecution from the Italian government, according to Italian media sources.
Ratzinger's meeting follows upon the apparent receipt by the Vatican of a diplomatic note from an undisclosed European government on February 4, stating its intention to issue an arrest warrant for Ratzinger, who resigned from his pontificate less than a week later.
http://itccs.org/
If it's true, might be not only why the Pope resigned but also why he's going into "seclusion" within a refurbished cloistered monastery inside the Vatican. IANAL, but wouldn't the Vatican be able to refuse to extradite him since they're a kind of sovereign nation?
Didn't see other diaries on this when I did a search and I really don't know anything about the source or whether it's all fabricated. Anyone out there who knows more?
(If it's junk, I'll delete the diary).