I never knew that. Where does it come from, does it symbolize anything particular?
Never mind - I saw the link.
Spock was my favorite character in the original series, and this is a bit of trivia I missed.
Nimoy's father took him to an Orthodox sabbath when he was a boy, and that made an impression on him.
Check the link I posted above, should cover it pretty well.
Leonard Nimoy was of the tribe of Kohanim, the priestly class descended from Aaron, the High Priest. Those members of a synagogue who are Kohanim assemble in front of the congregation on certain important holidays to bless the congregation with the special blessings given only by Kohanim. While doing so, they spread their fingers in the "Spock" way at the ends of their outreached hands. That gesture was where Nimoy got his inspiration for the "Spock" hand gesture.
This is what the Kohanim must have looked like during the time of the Temple. Look at the men in the back row, making the gesture of the priestly blessing;