Is horse meat safe to eat?
It is perfectly safe to eat (when produced, transported, and so on under sanitary conditions, just like any other edible meat).  

In some cultures it is considered a delicacy; in others, it is not considered appropriate to eat, but those issues of cultural norms, not of safety.

The news is because it is a violation of trust (truth in labeling) in a cultural background where horses are not normally eaten.  Personally, I might wonder what other shortcuts the purveyor had taken if they are lying about content...