That's what we did for Monero and it works wonder.

We should have dedicated team to handle announcements - not big ones, just like once a week. It is more important to give regular news that only big news with nothing in between. The Monero Missives teached me this.
This requires time and should be done by someone who like it (that's why I recruited foxy on Hyperstake). People who like and who know need less time and energy than people who don't. That's why I won't volunteer Better to have no manager than to have one who does nothing or almost nothing.
So, we have for communities to address: Twitter, Facebook, Reddit, Google+. Who wants to be in charge of (at least) one? Jessica would announce regular updates here, and every social network manager would publish an announcement as s/he sees fit on his/her favourite social network.