If you decide to go against Burke's wishes during The Power of the Atom (either by disarming the bomb, or by killing either him or Tenpenny), you will periodically be hunted by Talon Company mercs throughout the Capital Wasteland. The contract can be found on their corpses.
The contract is enacted even if the Lone Wanderer disarmed the bomb and completed the quest without ever meeting Burke.
Find <character name> and show how we treat people that fail to live up to Mr. Tenpenny's expectations. Do not fail me. You know what will happen if you arouse my displeasure.