[SURBL-Discuss] Software spam with recently registered (fake?) sender domains

In recent days I've seen a lot of pirate software advertised in spam that uses a sender address of the form

"Firstname1 Lastname1" Firstname2Lastname2@suspectdomain

where suspectdomain is a very recently registered domain (late August-early September).

Previously software spammers used all kinds of fake sender domains, but non they had registered themselves and not specifically recently registered ones. Has anyone else noticed this and has any thoughts about it?

I wonder if spammers are buying lists of recently registered domain names off registrars in order to poison domain blacklists?

Joe