The location of the event might be the biggest clue, several analysts said. As an entertainment capital, L.A. could offer the backdrop for media content on any new tablet, including games, movies, or more.

Some bloggers have suggested that a content-consumption tablet could be targeted at the $200 Kindle Fire from Amazon rather than the new $499 Apple iPad.

"If it is a game, or is entertainment consumption-oriented, then Tinseltown makes sense," said Jack Gold, an analyst at J. Gold Associates.

He said the source for TheWrap.com story could be mistaken, and Microsoft could instead be unveiling an Xbox portable device rather than a full Windows RT machine.

Gold said that if Microsoft does announce a Windows RT machine, it will probably cost $600 to $800, the price tag most observers expect other RT tablets to carry, "unless Microsoft plans to take a loss on each device sold because they have to buy the same components as everyone else."