At this point we currently only support Google ID's for login's but as I write this we are working on our OpenID implementation (best explained here http://en.wikipedia.org/wiki/OpenID) and that will become our standard for logins by the time we reach a public beta release. No logins that you create prior to that release will need to change as Google is currently an OpenID provider.
Is Open ID now in use? My works management would like to administer accounts from our Active Directory and the inability to manage accounts through our system is a security risk. As such they will not allow us to use google because of it's decentralized location on googles servers.