…announces her retirement from politics. Being a former NDP leader, one presumes this is just to set up her “comeback” in 5 or 10 years.

I’m not familiar with the local dynamics, but one would imagine that this puts Halifax into play:

2006 Halifax Election Results
McDonough (NDP) 46.9%
MacKinnon (Lib) 30.9%
House (Con) 18%
Wright (Green) 3.9%
Seed (ML) 0.3%

UPDATE: Rumours abound about possible NDP candidates.