Might be. My first thought after watching the video is that this "leak" seems to be done on purpose. It might also mean that the mockup on the table doesn't mean anything, but there's no way a person in that position would forget something as volatile as a new Nokia model laying around on a table when reporters are coming for an interview.

From the image it does indeed look Maemoish. There is the menu in the left top corner and the image on the screen looks similar to a current tablet desktop with a lot of widgets open.

But as it is just a mockup, I'd take it at the most as a hint of the design ideas that might end up in the final device. Or it could be the real thing

Oh yeah, and I think that the one on the right looks like boring as hell. I'd expect a bit more from the RX-51.