The authentication is similar to Facebook authentication but instead of Facebook it's obviously using some custom Sony thing.
I registered, and then when I went to sign in at the forums, it knew I was logged in on the Sony side, which is when XenForo took over and I chose my forum name, e-mail address, agreed to the forum terms and then I was registered on the forum.
Is that the gap padding and margin between the home and edge of the navbar which really exposes the issue on hover? If so I noticed that too because I corrected this on that w.i.p style i'm working on.
edit: oh right, between the .navTabs & .tabLinks. Yeah that does look a little odd. I think this might just be an oversight on their part as I had this problem with the sizes not being correct.