Here's a rundown from NBC News on the prophesy of St. Malachy- and why it may induce a bigger end-of-the-world scare than 2012, Harold Camping and Asteroid 2012 DA14 combined.
Bottom line: according to one interpretation of Malachy's forecast, Pope Benedict's successor will be called Peter II- and will be the last pope.
(Cue Twilight Zone theme) One of the leading contenders is said to be Peter Cardinal Turkson of Ghana.
Malachy, a 12th Century Irish monk, produced a list of what are said to be the final ten popes, together with a brief description of each. The interpretation of the list is controversial, and especially so is the genuine character of the final prophesy about the apparently apolcalyptic reign "in the midst of great persecution" of Petrus Romanus, whose papacy will supposedly see the return of the "terrible judge" (Christ).
Not much distinction of Law and Gospel there. As to the validity- and even the content- of the supposed "prophesy," you'll be hearing a great deal more about it in the next month or two- especially if Cardinal Turkson is elected.
HT: Real Clear Religion