CR has issued a prediction for PMA 2009, based on the rumors that they have received. PMA starts in about 3 weeks at the beginning of March, although a release of something is expected next week on February 17th/18th.
CR doesn't think the Canon EF 24-105 f/4L II IS Lens will be released at PMA:
"There's been murmurs about this lens for a year or so, nothing substantial has come of it yet. I think the current one sticks around for a while. People would go crazy if they upgraded this and left the 24-70 alone.
Again, this is their prediction based on rumors they have received.
Source: CR on 2/13/2009.