If you are using Google+ instead of, or in parallel with Facebook on your iPhone, you should update your client. There’s a refresh on the iTunes Apple Store which bumps the version numbers to 1.0.15.5173.

Aside from the usual bugfixes and performance improvements, you will be happy to find out the you can now use hashtags in your posts. Consult your App Store on the phone or your iTunes application on your computer to grab the update and spread the hashes to your circles.

Source: iTunes

Via: iClarified