That's the pejorative usage. There is also:

"Cult also commonly refers to highly devoted groups, as in:

• Cult, a cohesive group of people devoted to beliefs or practices that the surrounding culture or society considers to be outside the mainstream

  • Cult of personality, a political leader and his following, voluntary or otherwise
  • Destructive cult, a group which exploits and destroys its members or even non-members
  • Suicide cult, a group which practices mass self-destruction, as occurred at Jonestown
  • Political cult, a political group which shows cult-like features"

http://en.wikipedia.org/wiki/Cults_of_personality

http://en.wikipedia.org/wiki/Cult_following

http://en.wikipedia.org/wiki/Cult_%28religious_practice%29