First off:
I have very little experience with PHP.
But, if I've get this right, you'd want a certain picture to show when the server's up... and another one when it's down?
I've seen Javascripts that change pictures over certain commands. (simple, I know)
One of them, the simple weekdays one:
<SCRIPT LANGUAGE="JavaScript">
<!-- Begin
today = new Date();
day = today.getDay();
arday = new Array("sunday.jpg", "monday.jpg", "tuesday.jpg",
"wednesday.jpg", "thursday.jpg", "friday.jpg", "saturday.jpg");
document.write("<img src='" + arday[day] + "'>");
// End -->
</script>
Call me noob, as I'm only speculating with my own ideas, but:
Couldn't there be a way to edit such a Javascript for that purpose?
Instead of weekdays, in this case?
Is it possible to mix java with PHP?
This is where my experience so humby ends. -_-
Just doing my part.
IF you find a solution, please share it, would you? (I'm sure it's out there somewhere)
Best of luck!