From Wikipedia: "On and around April 17, 2007 secure (https) access to the orkut login server was no longer available. This may lead to compromise of orkut accounts and by extension google accounts as well as gmail accounts since the password for login is transmitted via cleartext."
Sure enough, the http login comes up (I had been using a shortcut to the secure login site). Note that the password used by Orkut is tied to your gmail account, so sending your login password via plaintext may compromise your other Google accounts. If you use Orkut, and you have signed in since April 17th, you should immediately change your gmail password, and avoid Orkut until they fix the secure login.