Will users be able to reg/login to application as a page they manage?

Gez,
Authentication with a "Page" isn't possible. Facebook only allows users/real people to do certain social activities on some websites and things like Authentication and the Like button are restricted to real people. Since one user can create unlimited Pages, it opens up a big avenue for abuse if that user can then create unlimited accounts on a site or click the Like button unlimited times.

I hope that helps explain,
Alex

I've never seen mention anywhere in the Facebook documentation that a Page can login to a website. To get an access token for a Page it has to be granted by a user, so I'm not sure how the Page would get one otherwise. Additionally, Pages don't have email addresses or other information (first name, last name, etc) that would be required to create the user profile. It's stuff we could ask from the user, but diminishes the point of social authentication.

If you can point me to website you saw that let's Pages login, we'll gladly look into it to see if we can understand what they are doing.

Thanks,
Alex