they are not doing it at the Registrar level(by contacting the registrar for the domain and forcing them to update the authoritative name server info to point to NS1.SEIZEDSERVERS.COM, NS2.SEIZEDSERVERS.COM), but rather through the agency who controls the top level domain. In this case, all the “seized domains” appear to be .com and the agency/company who has the ICANN contract for this TLD is VeriSign(which also controls .net TLD).
More details can be found here: http://rulingclass.wordpress.com/2010/11/28/the-background-d...