Some of you may have noticed the new Share button in SharePoint 2013.  Without going into great detail, the Sharing metaphor is plugged in throughout SharePoint as a means for anyone to request and grant access, for themselves or someone else.  If you are logged into a site where you are not a site collection administrator though, you may notice that the Share button is not visible.  What you need to know is that the Share option doesn't appear for non-administrators unless you configure two things in Central Admin...System Settings...Configure outgoing e-mail settings:

• Outbound SMTP Server - Sharing uses emails for notification for the various parties involved
• From Address - can be any value, doesn't need to be real, but if you don't have this set to a non-blank value then the Sharing options won't show up.  I don't know if this will be the case at RTM or not.

Sharing brings some pretty nice features into SharePoint 2013 so it's worth spending a little time on it to get to know it better.