The latest software version for the K3/Keyboard is 3.3.(
Keyboard Software Update Page)
I would not advise messing with the firmware of a Kindle you are giving to someone else. It will possibly prevent them from getting new updates that they might want to have - though I don't really expect any more for the Keyboard model. And it is against Terms of Service, though Amazon hasn't a history of bothering about it too much. Still, if it's not important to the recipient what pictures display when sleeping, having a "hack" installed may cause problems for the person if she needs warranty service.