I really like the mobile concept. I think (probably that is also your idea) that the icon arrangement of the second picture should be the same for the home, with an icon that opens the app gallery in the place of the unblock icon. Or better the icon for the exposť (open app list) in the place of the bottom lock icon and the icon to launch apps in the place of the top lock icon. I think it would be a really cool and simple interface with a clean home with a more elegant kind of dock (iphone and Android look almost the same). That would also keep the most important icons in the home (similar to the desktop concept of no icons on desktop) and other apps in a app gallery (similar to Android, and miming slingshot).
Now thinking about it maybe the bottom lock icon should be the home, and the top lock in the middle to launch apps. Back icon and exposŤ should be put somewhere else, maybe add 2 more icons next to the home icon and do something as it is in Android.
I really like the work you've done on Elementary OS Luna ! And I think you must also make an OS version which look like what you published above ! It would be great, and I think that people will like ! Just be sure to reduce technical specs of phones on which we could install it ! And, make friend with chinese manufacturers as ZTE and so on... They are more and more appreciated !
"Yeah but who's messages/notifications are you gonna see if there are multiple users that are logged in at the same workstation?" When it looks like on the mockup, it really is a good question. But in GS lockscreen is not just a list of users. It's like a normal session, just locked. So there will be notifications of user whose locked session is visible. (You see YOUR notifications, YOUR wallpaper, etc. If you like it of course.) Other user can just click "switch user" and he can log in or see his own (or somebody's else) lockscreen.
The second screen, showing the unlock gesture, looks really uncomfortable. I have the nexus 4 and I generally like the idea of sliding the lock to the left or right to answer/deny calls, but when it's used for just the sake of unlocking the phone I don't want to launch twitter or the camera app by mistake. The fact that "unlock" is straight up also makes it a really uncomfortable gesture - to the right would be easier for right handed people since you would be doing this with your thumb. This is something you would do often and if the OS has a well designed app launcher it wouldn't be necessary to have a shortcut to these apps on the unlock screen.
I'm trying to make sense of this, being righthanded: it's easier to swipe right instead of up? Are you sure you're right-handed? Swiping the thumb towards itself is not easier than swiping up on my hand.