Microsoft recently revealed that they were to announce something later today, very little information has been said about the event, but new photos seem to suggest it is about Office 2013. These photos show Office 2013 banners high above the entrance to where the event is taking place.
From the photo, we can see that Microsoft will be talking about Office, and maybe another product too, as it looks like there is a second banner waiting to go up, but that is currently just speculation.
The announcement will be made by CEO Steve Ballmer at Noon PDT time in San Francisco later today.
(Thanks @windows4live)Microsoft, Office 2013