Is there any canonical hint or reference in Star Trek: The Original Series about a romance between Spock and Lt. Uhura? Is their relationship original to the 2009 Star Trek film and if so, is their relationship commented on or explained by any cast or production crew? Was it to appeal to the "sensibility of the time" or just good storytelling?
The actual relationship was an entirely new invention of the writers of the rebooted Star Trek film, although they claim that they were riffing off the "flirtation" between Spock and Uhura seen in the Original Series
"There was a little flirtation in the original series," says Orci. "But we thought that since we were doing a harmony on some of the things that were happening before, well, what happened in the original series? The first interracial kiss was with Kirk. So we thought what can we do that's different, but that still pays homage to that? Spock!"
Interestingly, according to actress Nichelle Nichols the iconic kiss between Uhura and Kirk was originally written as being between Uhura and Spock.
"That was so funny, by that time, I didn't think of it as 'The First Interracial Kiss'. I just got the script, and I said 'Oh, wow, great! We're going to get a little romance in here!' [...] Not many people know this, but it was originally written as being between Uhura and Spock. But Bill Shatner said 'Oh no! If anyone is going to get to kiss Nichelle, it's going to be me!' And so they rewrote it, and we all laughed about it."
The flirtation between Uhura and Spock begins as early as Man Trap