Google Plus – How to Identify Page Owner

Under you name in Google+, you'll see a page menu (drop down), click on the arrow to see a list of your pages; click on a page to manage that page.

For more information, see http://www.google.com/+/business/

I assume it is the same as a Person's page, you can follow 5000 entities. The equivalent in circles I am not sure, but as long as you put 5000 users within your circles, that is the limit. The number of users that can follow you seems close to unlimited though.

(Source: Scoble - https://plus.google.com/111091089527727420853/posts hit it in September, the actual post where he says that, is too hard to find now)