"The ability to create with your friends online will come as part of the first major update after the game is released," reads a post by developer Sam_Protagonist on the official PlayStation forums. "Offline creating with up to 4 people on one PlayStation 3, however, is available right from the get go," he added.
Sam_Protagonist stressed that all other online and multiplayer features of the game are still present. Players can still play the game as a team online, share created levels online, and download levels made by other users.
As the developer pointed out, "[the delay] might actually be beneficial to creators ... as you'll be able to work out the tools entirely, and figure out how best to work with others."