Remember that rant I gave a while back? Well, I should have read the FAQ:
Q: Why are the expected arrival dates different for movies shipped on the same day?
A: We try to ship you movies from your closest shipping center. If a particular movie is not available at your closest shipping center, we will ship it to you from another location. This can increase delivery time, and therefore, it may have a different expected arrival date.
Ahem...I take it all back.