This offer presents a decent opportunity for those who want to try PS Plus although do not possess a membership. The free weekend begins on July 4th at 00:01 and will run until 23:59 on July 5th.
"We’ll be releasing a free PS4 theme later this week to celebrate 10 years of PS Plus. The theme will be available on PS Store for a limited time, so be on the lookout. For those of you who haven’t tried the online multiplayer benefit for PS Plus, we’ll also be hosting a free online multiplayer weekend starting July 4 at 12:01AM through July 5 at 11:59PM in your local time. (Online multiplayer game sold separately. Requires internet connection and PlayStation Network account.)"Source
Thanks to Mydealz for the heads up