A fair number of you have probably used the ridiculously simple (and bizarre) workaround to get Okay Google Everywhere working on your device without waiting for Google, but there's a catch. If you turn on the lock screen functionality, it makes your phone a little less secure.
All you have to do to place a call from the lock screen is say "Ok Google," and tell it to call someone. The problem is that anyone else can do the same thing. The dialer has special access to the system so it can pop up on top of the lock screen (like when you get an incoming call). At no point in the process of placing a call with OK Google Everywhere does it ask for your code to unlock the device, which is probably the intended functionality.
I'm just calling the power company in the video above, but it could be any contact you have saved. The person placing the call can see the full phone number, along with any alternate numbers you have for that contact as well. If you try to do anything while the call is ongoing, the device has to be unlocked, so it's still fairly secure. Although, you can also start turn-by-turn navigation from the lock screen via voice. So the "navigate home" command will tell any curious party where you live, and take them there.
If any of this is a concern to you, make sure you leave the lock screen box unchecked in the new Everywhere section of Google Now. It is unchecked by default, but the option could use a warning of some sort.