The last few phones that I had used, I had a different wallpaper in the lock screen and once unlocked it would go to my normal wallpaper and set up. Is this not possible as I could not figure it out and figured there was an app for it? Thanks
stock, this is not an option. i know at least AOKP had this option for their 4.1.2 ROM's. i am also assuming it is coming soon to the 4.2 builds.
but if you aren't looking to root and ROM your phone, you could check out widgetlocker. they have a pretty good lock screen app that you can keep it looking like stock, or completely change the look of it and it has an option for you to use a lockscreen wallpaper separate from your home screen wallpaper