OK, that was quick; Canon has acted speedily on the rebate checks problem that fell on their hands when their third party agent for rebates suddenly went under Chapter 11 protection.
Canon USA says you may cash those checks now. If your rebate check was returned unpaid, Canon said they are processing replacement checks now which will be mailed to you and you should receive in approximately ten (10) business days.
Full details of the Canon announcement at the link below.
[Site: Canon USA]