I had the same question and called GBCI two weeks ago. The customer rep confirmed that the MBCAG guideline for v3 is under development and has no date when it will be released. Meanwhile, projects registered under v3 cannot use the old MBCAG guideline. I think it is unfortunate, but I think if you have 2009 projects that you know can benefit from the old MBCAG you can potentially submit a CIR to build your argument.