Ooh, shiny!
A couple of quick 2AM comments:
1/ KUAL actions: the root fs is ro by default, and unless I completely forgot about a symlink, the upstart jobs live in /etc/upstart, not /etc/init
2/ You'll probably want to default to the correct filename (beware: depends on the target device) for the screensaver, or trigger a re-parse from the screensavers hack, because it won't do anything with a file named 'onlinescreensaver.png' without further action
[So, in the event of a second sleep session before the next update, you'd get a completely different screensaver, the only thing making it 'work' the first time is eips].
(That of course gets a bit more complex if the SS hack is in cover mode, but I think we're agreed that the two should be mutually exclusive anyway.)
All of that applies to FW 5.x devices, since:
1/ Before that, they used SySV init, not upstart
2/ And they didn't really care about the screensaver filenames
(Also, there's a leftover log in bin/stdout in your archive ;p).