There was another high-profile domain name highjacking this weekend of NYC’s ISP PANIX.COM, whose customers apparently suffered outages of service when the domain name was apparently transferred without authorization.
ICANN has a transfer policy that was born out of the Ack v. Nack wars between registrars, which policy specifies the quality and quantity of ‘acknowledgment’ between the ‘winning’ and ‘losing’ registrars and the registrant(s). One article suggests that the winning registrar simply didn’t follow the protocol here.
In the meanwhile, you should consider putting a ‘registrar lock’ on your domain name, which prevents this sort of thing.
A typical FAQ on registrar lock from Go Daddy is here.
Info on Domain Protect from NSI is here.
Dot Registrar’s DomSecure is here.