When a site is launched the proposal page on Area 51 shows a Rocket to indicate it's being launched. See here: http://area51.stackexchange.com/proposals/52519/network-engineering for an example. The rocket has a name USS-SE-1701.
I don't know how easy this would be to implement but would it be possible for that number 1701 to be changed to the proposal number on Area 51? For the example above the number would be 52519.