There have been a couple of occasions where a CMDR was sitting at Sag A* fragging people. I haven't heard any cries over the forums in the last few months on a Sag A* griefer.
Now, if you're heading towards Sag A* in open, just be aware of any CMDRs if you jump in, and be ready to jump out if it looks threatening. If you really want to be safe, switch to solo one jump out and enjoy the view, free from any potential griefing.
Not too many people hit Sag A* on a daily basis. It'd be pretty dull, waiting day after day in one spot, waiting for unsuspecting commanders. I could understand about six months ago, when a ton of the explorers out there decided to jaunt out there.
Not saying that there wouldn't be a CMDR there. Just keep frosty, and good situational awareness.