I agree with Joel, as evidenced by my earlier opinions on this matter. Untreated wood should not come in contact with concrete whatsoever. Building Inspectors will not allow it. Also, burying a post in concrete creates an opportunity for concrete failure despite the longevity of the wood. Wood expands and contracts with moisture content. At some point there will be space for water and therefore concrete detoriation due to freeze/thaw cycles. The deeper the post is buried the more likely any flexure due to wind loads will incur significant pressure on the concrete at the surface due to the lever action of the bending in the post, which ultimately could cause spalling, especially if weakened from the freeze thaw cycle. Lastly I'm not sure that I have confidence in any product remaining water tight for the long term, and even if it does, there will be water inside the post due to absorption from the air that can only wick out through the exposed portion of the post, not to mention water that ultimately might make its way down the side of the post on the inside of the "post wrap". I am unfamiliar with any accepted practice allowing wood buried into concrete.