Thanks to babyraver (who thanked gigglecam) for pointing this one out.
But basically, this means to me that you can never be sure who (or what) you're talking to (person or server) online. Because the government can seize the site. For now, yes, there are these cases where they are straight-forward about it, saying that the site has been confiscated/turned over in a plea bargain/etc. But is there any guarantee that this is what must happen? Could they take over LiveJournal without us realizing it? Take over slashdot? Or anywhere else?
If anything, this proves to me that the American legal system needs a significant rewrite to deal with "modern technology". Taking new technology and squeezing it into old models is getting rather difficult and impractical. What is a DNS entry anyway? Property, a tangible asset? Or is it merely directory information, like your name in the phone book? Do you own the domain name, or do you use it at the leisure of some provider?