they are banned until whoever first payed for its one year or how many year registration is up then you will be able to pay for it
There are several "google banned checker" sites online -- For example: http://www.iwebtool.com/google_banned Basically, from what I understand, a domain is considered "banned" if it once appeared in google's index then completely disappeared. You can request Google support to reconsider the domain for indexing. For instance, if you purchased a domain that was previously banned, you can email their support and request it be reviewed for inclusion.
Thanks for such great info, one of my friends going through with same thing, at least he can now email google for reconsideration.
I think no domains are banned..its just that some registry's like .US, ban certain keywords..so you cant use them while registering a domain in that extension..