Granted it's not an actual app but accessing Google+ on our BlackBerry devices has been made a tad bit easier with this mobile launcher. It saves us the URL typing time at least. Unfortunately this app is only compatible OS 6 devices right now so if you have anything below that please do not download.
By the way if you do have a G+ account and haven't done so already, find us and add us to one of your circles by going to the official BlackBerryOS.com G+ page to stay connected with latest BlackBerry news. Now Google, come on, we can be friends. Give us a real mobile app.