The action exposes the lie that the US government does not control the Internet or does not exercise that control and perhaps hastens the day of a fragmented Internet. It’s an example of the government’s hypocritical position on Internet freedom: how can we express outrage at countries that block facebook or censor google when our own country seizes domain names and, in another recent example, tries to pass an Internet Blacklist Bill to block file-sharing websites? To the hundreds of thousands who spoke out against the latter, kudos, but I submit that the former poses just as dangerous a slippery slope.
These companies are obeying the laws of the countries in which they are based. Who are we to block them let alone seize their Internet property?
Update 2011/05/11: More scary developments in net censorship.