According to Pierre LeBrun, The Senators have given permission to the Ducks to speak with Paul MacLean about their vacant assistant coaching position.
Having the Paulrus back in the league would be great for Ottawa since he has two years left on his contract at an unspecified salary. The benefits are a bit less clear for MacLean - it would be a definite cut in pay, but the apparent lack of interest in him for the vacant head coaching positions may motivate him to take a lesser position to stay in the game.
Ottawa would likely be eligible for compensation, a 3rd round pick in the next three years, if the Ducks hire MacLean. Changes are expected to come to that rule that would remove compensation for coaches and executives who have been relieved of their duties, however that is unlikely to happen very quickly.