Ya I can log in... but i wouldn't get your hopes up. If they just admitted you on friday then they might not have had time to activate the site for you yet.
The other thing though, and I don't know if this happened to other people, but I got an email that all-but said I was admitted. It was actually kinda funny... it was from Andy Cornblat, and he said that while the policy doesn't allow him to release decisions over email, he just wanted to inform me that I would be able to access the admitted students site w/in 24 hours, followed by, "was that subtle enough?" But again, I got the email after I had already received my package, so I still wouldn't discount it.