Microsoft is convening “a major announcement” in Los Angeles at 3:30 local time (or 6:30 Eastern) at a location that will not be unveiled to invited press until some time this morning. (Preliminary invitations went out only last Thursday.) They are expected to announce a Windows tablet of some kind, and presumably the LA-venue is telling for a strong emphasis on entertainment. Barnes & Noble’s Nook–in which Microsoft now owns a minority stake–will undoubtedly have at least a presence on a Microsoft tablet. From there the extent of the involvement is currently unconfirmed, with some rumors indicating the new tablet […]