I think the police usage of Facebook was inspired. It's free for the police, there's an existing distribution mechanism in place, it's highly scalable and it's canonical, which can quickly cut down rumors. Twitter became a festering swamp of rumors and BS, whereas being subscribed to the QPS facebook page meant high quality information.
I tried to get onto the Moreton shire council to find a road closures list, and was faced with a downloadable MS Word document. There's the two extremes for you.
One thing that governments everywhere should learn from this is that maintaining and using Twitter and Facebook from established, trusted accounts is a very good way of getting information out there. Even if only a tiny fraction of the population are subscribed, they can quickly disseminate information to neighbours and family members.
I think the BOM should look into it.