A Microsoft contest to guess Windows Vista's release date hints that the product's release date could be 1 December, though the company itself is remaining characteristically mum on the topic.

As reported by the IDG News Service on Monday, a contest through the Microsoft BetaExperience campaign for users in the EMEA (Europe, Middle East and Africa) region is offering prizes to people who guess the correct ship date of Windows Vista. The contest can be found here.

User can take a guess at the 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 30 November, 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 1 December, 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 US, as well as one of several Xbox 360 consoles.

Josh Kerwin, a spokesman for Microsoft from its public relations company Waggener Edstrom, said yesterday he could not comment on why 1 December 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 Vista will ship but is not representative of a timeline," Kerwin said.

He added that it's unlikely Microsoft will comment on Vista's ship date beyond what the company has already stated. Microsoft executives have said the OS will ship some time before the end of the year, most likely in time for the 'holiday season' in the US. That typically means before Thanksgiving, which will fall on 23 November this year.

PC Advisor conducted a test of the contest site by choosing other random dates before 30 November – days in February, June, July, August and October – to see if the 30 November/1 December change in videos is just a fluke. However, in the test, all the dates before 1 December show an array of videos that state the date chosen is too early. Similarly, picking several dates after 1 December shows a video that says those days are too late for Windows Vista to ship.