We didn't support 3GS because creating 2X the artwork would have been a lot of work for a relatively small % of iPhone users that will soon be upgrading to retina. Consider your comment a +1 for 3GS.

I also have a 3GS and I find this response a little baffling. It can't be that much work for you to produce non-retina artwork, can it?

iOS app dev these days is all about increasing what I like to term the ARPH (average revenue per hour), a function of the revenue generated per hour spent working on the app. The best strategy IMHO is to get something out there ASAP, validate the market, and then expand if the data suggests a viable product that people will pay for.

Our thoughts exactly.

Well we didn't want to do a simple scale-down, so some assets would have to be touched up, and other stuff would need to be remade. We're a small team so we did a cost/benefit and decided to focus on iPhone 4 and above.

It's not hard at all really, I've done it a few times. Since they've already designed for the Retina, shrinking to the 'old' display is peanuts.

Yeah, it's just a button, right?

Please consider me a +1 for 3GS. Looks like a beautiful application.

I would also like 3GS support...

We're going to add 3GS support :)

Doesn't work for the latest iPod Touch too.

it doesn't work with the iPad (3) either...

Yeah no iPad support yet. For this app to work though you kind of need to have the device with you at all times to not miss the reminders to leave for the airport. For that reason, we thought iPhone was the way to go.

albeit the iPad is not the most "mobile" device, it still is pretty portable, and used by many travel professionals (not the traveler per se).

still, looking forward iPad support going forward.

Also, there are a significant number of people out there with an Android phone plus an iPad.