The US government has shut down, because, apparently, that's a thing that can happen in 2013. The shutdown isn't some sort of rhetorical device or some legal technicality, the US administration is actually shutting down. All non-essential state-run organizations and agencies can't legally operate starting today.
This doesn't really affect the useless people that have led the country into this ridiculous situation, but rather the parts of the administration that actually does something, NASA for example. Thankfully, the shutdown, won't affect crucial missions, like the two US astronauts currently aboard the ISS.
Mission control is still operational, as well as a few other missions that can't be paused or shut down. But less than 600 people out of NASA's 18,000 will actually come to work during the shutdown.
Satellites and probes that are currently operational will continue to be maintained. But work on any future missions and launches will be halted.
Still, it's a ridiculous situation, especially considering how much NASA has already suffered in the form of budget cuts over the past few years.
It's even more ridiculous since all of this is over universal health care, something that most of the rest of the world decided decades ago that it was a good thing and an obvious right. But this is a country where gun control and abortion rights are still something considered debatable. A country stuck in the 19th century can't really be expected to run a space program.