I received my e-mail as well. I also could not find a way to accept the agreement. I've tried with Safari from my Mac and Explorer, Firefox, and Opera under Windows. The page's source has script code that asks you to check an acceptance box, but there doesn't seem to be either a check box for acceptance or a submit button on the page.
My impression is that you have to 'accept' this agreement before it will forward you on to the page where you can purchase the developer's license. The only reference to the $99 Standard Program, that I could find, is on their main iPhone Developer Connection page and it only supplies an 'Apply Now' button.
Am I missing something, or is this just an oversight by Apple on their developer's agreement page?