I saw this on Pistonheads as well.
I'd like to think it's the next variation of the LFA, but somehow i think it's just for parts or car dynamics testing. I thought I heard somewhere that Lexus dismantled a lot of the carbon autoclave ovens, but could just be a rumour.
If you haven't seen one, or more importantly heard one, in the flesh then I can tell you, you will not be disappointed.