What happens to delinquent accounts
Linden Lab will continue to try and bill the account for 7 days past the billing date. During that period the owner of the account can continue to login as normal.
On the 8th day, the account is put on delinquent hold for 30 days. Paying up the account during that time will reinstate it.
On the 31st day (or 38th depending on how you look at it), the account is closed, and the land turned over to Governor Linden.