To mention someone, just add a "+" before their name. After you type "+", you can start typing the person's name and select it once you have narrowed it down enough.
On the actual page where you publish a post, you can hover the person's name and you'll see a standard Google+ hover card with the option to add that person to your circles. Clicking the link itself will take you to that user's Google+ profile.
So, what do you think? Will you use this feature in your next Blogger post? I might use it if I need to tag someone. But for now I'll just tag myself to see how this works: +Michael Hazell .
