I thought it was pretty obvious when I heard his voice, and they modelled Sentinel's face to look like Nimoy...AND he throws out that 'Wrath of Khan' line just to eliminate any doubt.
I know that now! (now being after the movie but before you said it) that's why my only option is seppuku. I... uhh... don't have any sterile swords though...
Speaking of Transformers....I don't know of anybody remembers this happening during filming about a year ago.
Only part of that shot they used was like a second of Optimus pulling around the corner, cut it before any other autorobotos were even shown.