A Microsoft contest to guess Windows Vista's ship date hints that the product's release date could be Dec. 1, though the company itself is remaining characteristically mum on the topic.As reported by the IDG News Service Monday, a contest through the Microsoft BetaExperience campaign for users in the Europe, Middle East and Africa (EMEA) region is offering prizes to people who guess the correct ship date of Windows Vista. The contest can be found here.A user can take a guess at the Windows Vista ship date by clicking on a calendar on the site and hitting a "submit" button. If a user in the contest guesses the ship date as Nov. 30, a humorous video appears informing the user that date is too early for the product launch, and gives him or her the option to try again or confirm the guess. However, if a user guesses Dec. 1, the video informs the contestant that date is too late for the launch.Although the campaign and contest are aimed at Microsoft users in EMEA, anyone can enter the contest by signing up on the site. Users who guess the correct date are eligible to win a trip to the launch event in the United States, as well as one of several Xbox 360 consoles.Josh Kerwin, a spokesman for Microsoft from its public relations company Waggener Edstrom said Wednesday he could not comment on why Dec. 1 is the date the videos shift, but he said it does not prove when Windows Vista will be available."It adds to the intrigue of when Windows Vista will ship but is not representative of a timeline," Kerwin said.He added that it's unlikely Microsoft will comment on Windows Vista's ship date beyond what the company has already stated. Microsoft executives have said the operating system will ship some time before the end of the year, most likely in time for the holiday season in the U.S. That typically means before the Thanksgiving holiday, which will fall on Nov. 23 this year.The IDG News Service conducted a test of the contest site by choosing other random dates before Nov. 30 -- days in February, June, July, August and October -- to see if the Nov. 30\/Dec. 1 change in videos is just a fluke. However in the test, all the dates before Dec. 1 show an array of videos that state the date chosen is too early. Similarly, picking several dates after Dec. 1 shows a video that those days are too late for Windows Vista to ship.