hi, ICANN says 45 days but I think that it depends on the registrar, your best bet is to see where they registered it and check their policy on expired domains. most registrars have a grace period which gives the owner the chance to renew it.
If the website is live (or was yesterday) then presumably the domain name will be renewed. If the company has gone bust, then maybe it won't be renewed. You certainly can't jump in the moment it expires and snatch it off the previous owner.
Seems like a pain tbh, cant believe that a company can just 'waste' a domain... still thats life, ill keep an eye on it - its not crucial to me, though id like it im not prepared to cough up more than what a .com would cost me ie £10 or so