a few things aren't obvious to me after a half an hour evaluation. First impressions of v2.0 so far have been great (aside from a little hiccup with a cross pollinated $_REQUEST call...), and the new tutorials that were missing several months ago make all the difference. However, I cannot find anything related to content access restriction, or how to implement it. The Security tab doesn't seem to be related to content so much as functionality.

How do I a) restrict access to my content and b) allow people to register for my site so I can then grant them access?

Currently these features require a little customisation on a site by site basis. We'll put together some documentation about these features so that you can know how to get these things working.

This is a little over-due, but everyone searching the archives should know:

The access tab on the Site Content area is now used to do this.