Yes, seem rumours around the net today - perhaps we had this news five months ago?
Check out an old Geekzone article, from May, about a little text I've found on a local magazine, that could reveal more about the company doing this (more rumours?).
From the Infoworld link below: "The Smartphone, which is being produced by "a company with considerable experience of the wireless space," will offer "some radical innovations," according to an e-mail invitation sent by a public relations company for the unnamed mobile handset manufacturer.
"We can't reveal the company because of non-disclosure agreements, but I can say that it will be a global launch and that the manufacturer has a range of Smartphones on the way," said Lewis Webb of the U.K. public relations company AxiCom."
Update: regarding the link to the magazine in the previous Geekzone article, my source at Microsoft just e-mailed me "We ran an innovation event a while back in the swanky viaduct apartment but we were showing off the iMate phone along with other stuff like Smart Display, Media Center PC and Bluetooth mouse and keyboards." So, perhaps the magazine report in May wasn't correct?