Re: What happened to "OK Google"
The Google implementation only allows "ok Google" to work when you're in the Google Search app - which, if using the Google Now Launcher, is any time you're on the home screens, in Google Now or looking at results from Search (all technically the same app). It won't work from within Google+ for example, or when the screen is off, etc. Samsung's implementation is a little different so they obviously added to that. Part of what allows them to do that is the functionality built into the S800/S801 SoC that allows for "always listening" but so far I haven't seen another implementation that allows full functionality like on the Moto X (from any state, screen off or on, in any app, etc) although I know I was able to mimic that functionality with Tasker and some of it's addons on a rooted device before I got my X. At this time I also haven't seen the iOS version working on a device yet, so I'm not making any guesses at their execution.
Originally Posted by Fr0gburp3r