Yeah, I should have clarified a bit...
I got the same low credit limit details when I applied, and called up imediately after doing so. I was told to the credit limit listed online was not necessarily the same as the card would show up with, and any request for a limit increase would have to take place after the card arrived.
A week later, it arrived with the same credit limit mentioned when I applied online...that's when I called in with the cancellation threat, and got the bump within 30 minutes.
Given the different responses here, it sounds like Citi has some formula for determining these things, possibly independent of credit rating. Our credit is excellent, but it's nothing I would consider unusual...perhaps they were more flexible, given that this was our first Citi card, and our credit history doesn't have numerous open/closed cards on it.