One thing is clear in the deadbolt dustup on the Brownstoner.com forum: Landlords only have to provide a "working" lock. Anything beyond that, to quote one comment, "including window gates, alarms, killer attack dogs" and the deadbolt installed by the tenant who started the thread, is the renter's responsibility.
"You lost your chance to have the LL pay for it by not asking for the deadbolt installation before you signed," says one, noting that signing the lease means you accept the apartment as is.
Who owns the lock once it was installed, with the landlord's permission, is where commenters clash. Standard leases apparently stipulate that alterations and installations become the landlord's property (though the landlord can still charge you for the cost of removing alterations made without permission in writing). Probably the best the tenant can do, say the Brownstoners, is ask to split the cost difference, since the lock will enhance the next renter's peace of mind and thus the apartment's value.