Marc Garneau is now Liberal house leader

A quick announcement: Marc Garneau (Canada's first astronaut, former head of the Canadian Space Agency and MP for Westmount Ville-Marie) will be the Liberal house leader in the upcoming Canadian parliament, quite a different post from his previous position of science critic, and the more visible role will help show whether Garneau should become the permanent leader of the party later on or not.

As for exactly what a house leader does:

House Leaders

Each recognized party appoints one member to be its House Leader (a recognized party is one that has a minimum of 12 seats in the House of Commons). The House Leaders of all the parties meet regularly to discuss upcoming business in the Commons, how long bills will be debated and when special issues will be discussed.