PrintGet used to rumors. All organizations have rumors. Elvis spottings aside, there is often a kernel of truth in rumors, and you should know how to find those kernels.
If you continue to hear particulars about your company through the grapevine, if these rumors are consistent in content or if they pertain to reorgainzation, listen closely. Pay more attention to business rumors, such as who is sending company secrets to the competition, than to personal ones, such as who is dating whom.
More important, even if individual rumors turn out to be false, the volume and tone of the rumor mill can be telling. The grapevine tends to rev up when people are uncertain about the future. If groups within the company are discussing with one another behind closed doors, pay attention.
This may mean that official communication has broken down. Perhaps people lack information and some proactive team building is in order. This would be a good time to take steps to reinforce employees' sense of the big picture.