Universe Today -- a great site, and one you need in your daily web-reading routine -- has a story up that NASA may have to bring the crew on the International Space Station back to Earth by mid-November.
This drastic measure has not yet been decided, nor will it be for a couple of months. The basic reason is two-fold:
1) The Russians are having a problem with their unmanned Soyuz rockets used to resupply the station. A rocket launch last week failed to achieve orbit due to an anomaly in the third stage, and the capsule was lost. The astronauts on board the space station have supplies that can last for quite some time (the final Shuttle mission brought up quite a bit), so the loss of the cargo was not so much an issue. The real problem is...
2) The ISS currently has two Soyuz capsules docked to bring astronauts home. These docked capsules have a lifespan of about 200 days due to fuel issues. One of them is supposed to bring three of the six astronauts home in September, leaving one capsule for the other three in case of a problem. A new crew of three was supposed to go up later in September, bringing the total crew of the ISS back up to six, but that mission may be delayed. If there's only one capsule docked, only three people can leave in case of emergency, so the new crew must wait until a new capsule docks before going up.
If the Russians cannot get their rockets working by mid-November -- about the time that 200 day period is up for the second docked capsule* -- then the astronauts either take that capsule down, or stay aboard with no safe way to return home. The safe thing to do then is de-crew the station.
The Universe Today article has the details. Mind you, even if we still had the Shuttle program going, as I understand it this would still be an issue. For one, the problem is with the limited lifespan of the Soyuz capsules already docked, and getting a Shuttle up there wouldn't help that (except to be able to take the entire crew back to Earth; without a working docked Soyuz they still can't leave astronauts there). Second, planning a Shuttle mission takes a long time, and I doubt that NASA could've gotten one put together that quickly (unless, by coincidence, they had one ready to go anyway, but even then they still need a working, docked Soyuz for the remaining crew). Third, the reason the Shuttle retired is because they were getting old, and each launch was a bigger risk than the last.
So the least risky thing to do, if the Russians can't figure out and fix the Soyuz rocket problem, is to bring the crew home, and wait to put the next crew up there when things are back online. The ISS can operate relatively safely in orbit for a while without people on board; that's not optimal, of course, but possible.
This sucks, but it could be worse. That rocket failure was unmanned, so no one was lost. The ISS crew does have a lot of supplies, so they're in no immediate danger. The best thing to hope for here is that the Russians get this fixed -- and there's word they may have found what the problem was, an important first step toward the solution. I'll note that SpaceX is looking to have a capsule dock with the ISS in November, but it's not clear exactly how this new situation affects that plan. The Dragon capsule is not human-rated, and unless there is clear and present danger to the crew they can't return in it.
* The situation is actually complex, having to do with landing sites lining up with the ISS orbit as well as shortened daylight hours as winter approaches, limiting landing times.