I had noticed over the past few months that my iPhone's standby battery drain was higher than expected, but I'd put that down to the iPhone 5 potentially not being as long lasting as previous models.
Turns out it's likely that the real culprit is the most popular iPhone app of all time: Facebook.
I haven't conducted any scientific tests (yet) but by manually killing the Facebook app (and just to be sure: Facebook's Messenger app too) after each use, I seem to have made a very noticeable difference to my iPhone's longevity.
This is despite the fact, that for the Facebook app at least, I have all push notifications and badges switched completely off.
It's puzzling because I'm normally the first to lecture friends that they should never need to manually kill an app at all, and certainly not for battery conservation reasons. It seems like the Facebook app is using its VOIP status to keep active (doing non-VOIP related things, I imagine) in the background, specifically against the design pattern that Apple intended.
Considering it's the most popular and most used app on iOS, this extra drain actually represents an issue with significant platform harming impact. To that end, I hope that Apple are on the case and Facebook can properly fix it.
What's also interesting is that although I have now found quite a few articles about this, it's not common knowledge and certainly hasn't percolated through as a mainstream (tech) news story, despite the day to day impact it will be having on the vast majority of iPhone users.
It also represents a potentially worrying preview of what's to come with iOS 7 multitasking. Yes, the OS is supposed to keep strict control over background activity scheduling, but, as the above iOS 6 abuse shows, it'll only take a few badly designed apps to waste a lot of battery life requesting CPU time they don't need.
I would be interested to hear how anyone else trying this gets on; let me know via Twitter.