If you count Pete Wentz and Patrick Stump tweeting audio clips and photos as confirmation that Courtney Love and Elton John have collaborated with Fall Out Boy on their upcoming album, "Save Rock and Roll", then it's confirmed.
Pete tweeted this 5 second audio clip featuring Courtney, which features her saying, "It's Courtney, b----." (Of course, it could also just be a spoof of the Will-i-Am and Britney Spears track where basically all Britney says is, "It's Britney, b----.")
(WARING:clip is uncensored, so NSFW).
Not to be outdone, Patrick Stump tweeted this pic of himself with Elton Joh, with the hashtag, #saverockandroll: