[Update : Microsoft has officially quashed this rumor, confirming again that they have no plans to release games on HD-DVD. The full statement is available on the GamerscoreBlog.]
Xboxic has a scan from a page of trade newsletter Consumer Electronics Daily (CED) that seems to indicate Microsoft is considering releasing games for the Xbox 360's HD-DVD add-on. According to the article, Microsoft Game Studios head Dave Luehmann said that "Microsoft hasn't determined yet whether to do Xbox 360 games in blue-laser HD DVD," though he confirmed that there will be no HD-DVD games available this holiday.
If true, this statement would contradict a previous statement from Microsoft Corporate Vice President Peter Moore that the drive is "focused purely on movie playback." However, the CED article seems to paraphrase most of Leuhmann's comments, so it's possible that this is just a case of miscommunication.
Microsoft didn't immediately respond to a request for comment on the issue, but we'll be sure to update you if and when we get official word.