We're told much of the fleet was present in that system around the time Vulcan was attacked. Any guesses as to what they were up to?
As an aside, from a writing standpoint, the whole bit about some of the fleet being elsewhere was probably there to just drive a wedge between Kirk and Spock and to generate conflicting viewpoints - Spock wanted to meet up with the fleet, Kirk wanted to take on the Narada solo... they disagree, Kirk gets kicked off the ship, the story moves forward.
But it's still fun to speculate what was going on. Sounded pretty important.
As an aside, from a writing standpoint, the whole bit about some of the fleet being elsewhere was probably there to just drive a wedge between Kirk and Spock and to generate conflicting viewpoints - Spock wanted to meet up with the fleet, Kirk wanted to take on the Narada solo... they disagree, Kirk gets kicked off the ship, the story moves forward.
But it's still fun to speculate what was going on. Sounded pretty important.