Sony Computer Entertainment UK boss Fergal Gara has been talking about online play on the PS4.
Regarding the need for PS+ to play online he said they did this for 2 reasons:
"First of all, we wanted to introduce the console at a healthy price-point compared with PS3"
and the second reason was to give them the ability to introduce new features and and improve network performance.
Perhaps more exciting for Sony fans is that he confirmed cross game chat is coming to the PS4.