Fallout 4 has already all but stolen the show at E3, and Bethesda showed some new footage of the game during its press conference before dropping a huge bit of news: Mods created on the PC will be able to move over to the Xbox One version of the game.
Fallout 3 will also be included in the Xbox One version of Fallout 4.
There were few details given about how the mods will work on Xbox One, but this is a big step forward for console gaming, and should do much to increase the value of the game on the Xbox One. This feature was not mentioned as an exclusive to the Xbox One, so it's very possible this feature will also come to the PlayStation 4.
Update: Bethesda Game Studios' Todd Howard told Geoff Keighley on YouTube's E3 stream that the modding feature is currently exclusive to Xbox One, although it won't be available at Fallout 4's launch — it will be added to the game in 2016. Howard also said that he wants to bring the feature to PlayStation 4.