1. Web version - typical Facebook style, describes specific permissions but there are only 2 options that devs can use: read or read/write (plus read/write + direct messages but that will be gone this year)

2. iOS version - menu slides in with all of your system authorized twitter accounts, you tap the one you want

I'm pretty positive #2 does not give you any real authorization messages or screens. I just logged out of Meerkat to find out but that screen doesn't work anymore because their keys are broken