UPDATE 27/11/19: ConcernedApe has now released the full changelog detailing all the new content to hit Stardew Valley this week.
On top of all the changes mentioned in the article below, there are interesting new additions like new events, clothes tailoring and dyeing, hundreds of new items, and some all new areas to explore.
There's a new mineshaft dungeon right next to the quarry with new Haunted Skull and Sludge monsters, and if you reach the end of this dungeon you're rewarded with the new Golden Scythe. I accidentally found this dungeon playing last night and discovered these new enemies are pretty tough, though I also learned (from them killing me) there's a quality of life change when you "die" in Stardew, where it will show you a list of the items you've lost.
Your farm can have some new additions now too, with a shed upgrade, Fish Ponds, a new building called the Desert Obelisk, and more. There are some delightfully weird sounding new things too, like a Trash Bear that will come to clean your town of trash from year three onwards, and a new hidden subplot if you've turned your children into doves (because apparently that was something you could already do?).
This is by no means an exhaustive list of everything new, so to see the rest of the new stuff, improvements and fixes check out the full changelog here.
ORIGINAL STORY 13/11/19: Stardew Valley creator Eric Barone (or, ConcernedApe) has finally announced the game's next update will arrive on PC on the 26th November - with the console and mobile update to follow a few weeks after.
One of the main goals of the upcoming 1.4 update is to fix any remaining bugs in the game, as well as bring in some more quality of life features to make the game more "seamless" to play.
Some of these improvements include altering certain items that didn't have much use previously - the example Barone uses in his post is the Wild Bait used for fishing, "which used to be essentially worthless... but now gives you a chance to catch double fish".
It's not all about these minor changes however, as the free update will also introduce a bunch of new content. The developer doesn't reveal too much, but mentions there's a new unique event for each character after marrying them, and there's more endgame content being added to keep you busy.
The last little piece of new info for the 1.4 update is that a screenshot button is being added to the options menu, so you can finally take a snap of your entire farm.
We do know a bit more about what the next update will include, though - back in April, it was revealed a new map type would be added. Named "Four Corners", the map will allow players on a multiplayer farm to split their money pool, so you can have your own separate funds without having to worry about your mates spending your shared cash.
Stardew Valley is available for PC, PS4, Switch and Xbox One - the latter of which now has co-op multiplayer like the rest, after issues porting the last update to Microsoft's console.
The game is also available on iOS and Android, and while these will get the 1.4 update, there are no plans to bring multiplayer to mobile just yet.