Microsoft’s announcement Monday is set to start at 6:30 p.m., Eastern, and speculation about what the company is revealing is getting wilder as the day swings on.

There is a general consensus that Microsoft will show off a tablet. And, with Barnes and Noble telling news outlets that it is not participating in the event, it seems increasingly likely that the company will show off its own slates that run on the Windows 8 tablet software, Windows RT.

Microsoft entering the hardware tablet space would be a big deal, as it tries to move ahead in an area where it’s had what could generously be called only limited success in the past with the Zune and the Kin.

When it comes to hardware, the only thing that Microsoft has seen unqualified success with is the Xbox. If it’s going after the same software/hardware integrated model that’s propelled Apple’s iPad to the top of the sales charts, it will have to deliver something equally as compelling.

To do that, the company would have to play to its strengths by offering good Microsoft apps (Hello, Office?), a compelling option for serious gamers and enough power behind a tablet to actually do both. Hooking into its Xbox multimedia ecosystem, as the tablet is rumored to do, would be a good start and something we’ve already seen glimpses of with the company’s Smart Glass announcement at E3 earlier this month.

Holding the event in Los Angeles has raised a lot of chatter that the device will be entertainment focused, which strengthens speculation that it may have something to do with Xbox Live.

Speaking of the console, there’s another theory out there: that Microsoft will unveil something called “Xbox Surface,” a 7-inch tablet that will control an Xbox., a blog devoted to Windows coverage, spotted a specifications sheet on that detailed the tablet device and a “stationary device” believed to be the Xbox, since the device mentions the game console by name.

Surface, of course, is the name for Microsoft’s table-sized touchscreen, chess-game carrying examples of which grace just about every Microsoft store in the country. Samsung makes the 40-inch Surface the company sells today, and it’s meant to encourage collaboration. The name on the leaked spec sheet — if true — indicates that Microsoft may be trying to shrink that idea down to a more manageable size.

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