We have not received any of our expected observations of comet ISON due to a spacecraft problem. Communication with the spacecraft was lost some time between August 11 and August 14 (we only talk to the spacecraft about once per week). The last communication was on August 8. After considerable effort, the team on August 30 determined the cause of the problem. The team is now trying to determine how best to try to recover communication.
As long as controllers are communicating with a spacecraft, there is hope. When they are not in communication with a spacecraft, that's pretty scary. Good luck to the Deep Impact team on recovering the spacecraft for a future comet or asteroid encounter. It's a great little mission.