Rumer is it’s a tablet to be made by Microsoft, like the XBox. http://mashable.com/2012/06/14/microsoft-is-launching-an-ipad-killer-report/ This just in from Mashable: It’s hard to recall another Microsoft invitation like this one. No graphics, no details, no leaks. It sounds, well, almost Apple-esque in its urgency and stringent requirements and rules: This is a non-transferrable invitation, however, if you would…