[dkim-ops] Bogus DKIM signatures?

[Jim Fenton]

I heard two reports today of DKIM-signed spam being received by GMail 
users, and got a sample from one of them.  The message, from an IP 
address in Romania, had an obviously-doctored DKIM signature.  They took 
a yahoo.com signature from late April and changed the d= to mahoo.dom .  
Same with the DK signature.

Anyone else seeing anything like this?  I'm wondering why they think 
this might be a useful thing to do.

-Jim