Is the forest service at fault? No way. Perhaps they had a chance to prevent this from happening, but the responsibility should lie directly on the shoulders of those that chose to go camping in the great outdoors. Having said that, I am not sure our court system will support that sentiment, in fact they probably won't.

Our societies continuous slide towards complete abandonment of personal responsibility and removal of the action-consequence relationship is sickening.

If a civil remedy is being pursued under tort law, the argument in the courts will likely revolve around the concept of whether or not the USFS and/or employees had a "duty" to act, act in this case meaning informing or warning folks about the recent bear activity, taking closure action, etc.

The elements needed to prove negligence, if that is the route that the plaintiffs go, are the following; 

1.  a clearly established duty to act
2.  a breach of that duty (either by action or inaction)
3.  causation (linking the action/inaction to damages)
4.  and damages

I agree with Dave in that I think it is good practice for organizations like the USFS to inform and educate whenever possible and appropriate, but I really don't like the precedent that would be (and is being) set throughout our country of allowing individuals to escape personal responsibility and the consequences of their actions. If you choose to set foot into the great outdoors, you shouldn't need to be told that there are a lot of things that can kill you out there. Sadly, there has been a huge erosion of what was once common sense, and we are trying to compensate for that by creating policies, procedures, and organizations to regulate, mitigate, and insulate.

Do I think that the organization involved should have mentioned the fact that there had been recent bear trouble in the area?  Absolutely.  I definitely do not think that they should be held liable for what happened though.

I'd be willing to bet the lawyers will dig something up that points out some public safety component of the USFS directives and mandates and will try to prove a breach of that "duty." Bummer for all involved.