From the Porter Airlines Facebook page:
JetBlue & Porter are partnering to give you more! Now fly to sunny Fort Lauderdale, Orlando, Las Vegas and Los Angeles from downtown Toronto with Porter & JetBlue.
The only catch is.... You'd need to connect in Boston. Porter only flies the Dash 8-Q400 so they can't get to any of those destinations themselves. The other thing is that Porter uses Toronto City Airport (Billy Bishop) (YTZ) which currently has a restriction on jet aircraft.
Porter is essentially Canada's version of JetBlue with an all-coach cabin with 34 inches of pitch standard for all seats. The only downside is no IFE.
As with all other JetBlue partnerships, through-ticketing and baggage interlining is expected to be the extent of the relationship with no reciprocal points earning/redeeming benefits.