I believe the item that Ben took out of the vent is the Black Rock ledger. I think he stole it from Whidmore the night he went to tell him that he was going to kill Penny. Whidmore was in bed asleep and woke to find Ben at the foot of his bed and they had the whole "we can't kill each other, but I can kill your daughter" conversation. That same night Ben took the ledger from him for two possible reasons.
1) The ledger contains some important information that would make it easier for Ben and the Oceanic 6 to find the Island.
Clearly Ben has some type of plan and may or may not need the ledger to get back, but I think it is key to determining its location.
2) By stealing the ledger, Whidmore no longer has access to the critical information inside the ledger, thus making it harder for him to find the Island.
We know Ben and Whidmore are both trying to find it and "the race is on." So clearly by stealing the ledger, Ben puts himself in a better position to find it again and hinders Whidmore in his search.
Theory by Tank
1) The ledger contains some important information that would make it easier for Ben and the Oceanic 6 to find the Island.
Clearly Ben has some type of plan and may or may not need the ledger to get back, but I think it is key to determining its location.
2) By stealing the ledger, Whidmore no longer has access to the critical information inside the ledger, thus making it harder for him to find the Island.
We know Ben and Whidmore are both trying to find it and "the race is on." So clearly by stealing the ledger, Ben puts himself in a better position to find it again and hinders Whidmore in his search.
Theory by Tank
