They mentioned that it may take a few hours before this feature is enabled. My guess is to wait it out.
Also, have you checked your Personal Information in Setup to see if maybe Apex Pages Editor Mode is disabled (it is by default, I believe)? If this option is not present, then your account has not been updated yet.
You will also see a Pages option under Setup > App Setup > Build when VF has been enabled for your account.
The vast majority of logins that had requested access (including all webinar attendees) should have access. A few, however, could not be processed. If yours is one of these, either try self-enabling via this link (use the shortcut option) or send me your Developer Edition username.
Also, have you checked your Personal Information in Setup to see if maybe Apex Pages Editor Mode is disabled (it is by default, I believe)? If this option is not present, then your account has not been updated yet.
You will also see a Pages option under Setup > App Setup > Build when VF has been enabled for your account.