iOS 6.1 and Background Audio

I asked about this in the iOS forum and didn't get much response. I realized I probably should have asked in the iPhone forum since this is IP5-specific for me...

I have tried looking through several threads on this topic, and maybe I am especially obtuse, but I'm having a hard time figuring out what has changed between 6.0.1 and 6.1 with regard to background audio. Some people are saying they're having trouble with YouTube, but I'm wondering if it's a general issue. I am on 6.0.1 and I've noticed that Atomic Browser shuts off audio if I leave the app or lock the phone. Safari seems to work though. I am wondering if I should expect even less functionality in 6.1.

Hmm...OK. I am wondering if anything changed with other apps/sites vs. 6.0.1...

The main thing is it isn't clear to me if anything changed between 6.0.1 and 6.1, or if it was just changes with apps. I see people talking about issues they're having but I can't find information about what changed at the OS-level.