Canonrumors.com has posted a rumor that I've also had confirmed from another source.

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Part of canonrumors' post is (I highly suggest you read the whole thing – didn't think it was fair to just copy all of their text):

“The 5D MarkII will have 24p, it is already in a firmware running in testing.  It was not released due to time but it was planned to be released with the manual control.”

Thru another source, I've also heard that there's a version of the firmware that has 24p included.

Please read the whole post over on canonrumors