I had been using Manatee myself, but my wife recently made a dedicated boarding pass scanner app. The thread about the app is here. The app decodes the string that appears in manatee, so it's easy to see the different data fields.

You can download the app directly from iTunes.

I downloaded the app via iTunes eariler. It plays nicely with US issued mobile BP's. However, I have a bunch of AF/KLM BP's on my desk, and when I try to scan those in the app, it crashes.

Boarding Pass Scanner App
 

Just a heads-up, what should be a fix for some boarding passes causing the app to crash was submitted to Apple. I'll post again when the update is in the App Store and will. Encourage you to try again if you've had issues before.

And the update to version 1.1 is now available. Please do give it another go if you previously had crashes, and let us know if it's fixed. (And if it's not, you should now get a much more useful error message instead of a crash)

Passbook
 

If you have a iphone, passbook works perfectly. If I get my boarding pass sent to my phone, it automatically puts it in passbook, with the tsa pre check and all.

IslesFan - an updated version was released after finding a small bit of noncompliant data in some AF/KLM boarding passes; should work better now!

Updated to version 1.3 - Spirit Airlines, in particular, makes a small error in the bar code. A few other random special cases have been accounted for.

Will try it again tomorrow morning.

Just to let you know, I was able to scan an AF BP I have from 2013 just fine and the data looks to be parsed correctly. However, when I scroll to the bottom, the app appears to crash. I'm not sure if it's because I'm jailbroken (I'm running 8.1 Jailbroken).

EDIT: It's a AF BP that has 2 segments on it. I also have some AP BP's that only have the 1 segment, that appears to work fine.