Sony announced that the online multiplayer feature of the PS4 will be available for free this weekend. This feature is usually only avaialble for PlayStation Plus subscribers.
Players without PlayStation Plus will be able to play online starting on the 26th of September at 8am BST until the 29th of September at 8am. With Destiny now on the market and games such as FIFA 15 releasing this week, this seems like the perfect opportunity for PS4 players to enjoy some online experience for free.
Sony confirmed that this offer is only for the online multiplayer and doesn't include other features of PlayStation Plus.
Source: Playstation Blog