I called the 650 number and spoke to customer support at Obopay. The lady told me that they are actively working on getting Billmonk up and running and that it should be up today (Monday Sept. 13th). I also recommended she let the concerned folks @ Obopay (no pun intended) know that there are rumours out on the internet that billmonk is down for good and that a lot of people, who maintain their accounts and have money owed to them, are getting antsy. Hopefully there will be official word from the guys @ Obopay very soon.
HTH.