Jumping in here. I just set up my account today and that threw me at first, too. But "Subscribe to" is the same as adding someone as a friend. "Grant access" is what you do to give them access to your journal and what they do to give you access to theirs. It's like friending and friending back.

I love that they have a FAQ for people from LJ. I wonder if they've always had that or if they're aware of how many people are defecting. ;>)