Apparently is the Google Smartwatch real, and have been seen in the Berlin, Manchester and Mountain view Google headquarters. It will have the same UI and features as Google Glass, with Google Now-like cards that you can swipe. It will not be a standalone device, it needs to be tethered to a smartphone. And of course it will be Motorola that will make the hardware now when Google owns Motorola Mobility. They have actually already made a smartwatch that was quite good a while ago.
I have no idea if this Google smartwatch will be presented on Google I/O on Wednesday, but it could show up as one of the Google surprises there. It will be very exciting to see if it will show up :)