Play.com has listed a Transformers Trilogy Set for DVD that has a tentative release date of November 28th. At the moment, it costs 25 pounds (Europe). It is noted that the cover art is subject to change.
Also, there have been many rumors going around that there is an extra 3 minutes of footage on the Walmart Blu-Ray exclusive. Nothing has been confirmed, so check back often for any updates. Remember, nothing has been confirmed. I don't want to get your hopes up too much in case this proves to be false.