Gamereports reported the following:
2006/02/22 13:30:11: By DM
It seems the official Rainbow Six web site has added a countdown marking the hours, minutes and seconds "until a Major announcement" is made. As of now, the news is less than 12 days away. We have also discovered that the countdown began at t-minus 360 hours, so of course we speculate that an Xbox 360 Rainbow Six game will be revealed eventually. More as we have it.
Cannot wait to hear the news! Unless the news is that Clancy is publishing a new book