From the Globe & Mail:
The new fine for impoliteness is just one of a number of bylaw changes that went into effect Monday, with riders who prop their feet up on a seat, or those who lay down on a row of seats, now facing potential fines.
The new bylaw concerning priority seating doesn't mean that it's an offence to sit in the area of a bus or subway that's reserved for the disabled; rather, fines can only be issued if a rider acts “in contravention of instructions” from a special constable to remove themselves.
EDIT: Turns out Ottawa's got courtesy by-laws, as well. From the OC Transpo website (H/T to 'anonymous' in the comments):
18. (1) A person with a disability, an expectant mother, a person with a visible need for priority seating, a person with a child in a carriage or stroller, a person with a Priority Seating Card or a person with an Assistant Card is entitled to priority seating on a front bench seat but is not guaranteed a seat.
(2) No person, who is not described in subsection (1), shall fail to surrender a front bench seat to a person entitled to priority seating.
35. (1) Any person who contravenes any provision of this by-law is guilty of an offence and on conviction is liable to a fine pursuant to the Provincial Offences Act.