They do have a full time security department: https://ssl.apple.com/support/security/
And believe me, they take every aspect of security into account.
I wonder how much of the threat profile involves corrupt shipping workers and other inside jobs and how much involves grand iPhone heists.
(Wardrobe, not central casting)
When I went to WWDC10, I was struck by the small detail of the conference security wearing black polos with the Apple logo and "Security" under the logo. At most conferences, the security is wearing jackets straight out of action movie central casting (e.g. "SECURITY"). I thought that was a nice small detail - to attire the rent-a-cops in Apple gear. But, now, reading this, I think they may have been full time Apple security staff. Security is paramount.