Update:
4J Studios detailed how to transfer your save:
.@TPC_IRL To transfer a #MinecraftPS3 save, go to the saves list, move to the save you want to transfer & press R1 to bring up Save Options
— 4J Studios (@4JStudios) September 17, 2014
Original Story:
Arriving right on schedule, patch 1.07 for Minecraft: PS3 Edition is now available to download, with 4J Studios calling it a “small update” and saying, “It adds a feature allowing save transfer of PS3 worlds for #MinecraftPS4.”
Since the world sizes in Minecraft: PS4 Edition are bigger than the PS3 Edition, people have been wondering why the transferred PS3 worlds can’t be re-sized. 4J Studios replied:
We’re intending to add functionality to allow you to re-size a PS4 world in a future update.
When any future updates for Minecraft on PS4 or PS3 are released, and when the PlayStation Vita version gets a release date, we’ll let you know.