Harmonix will release Rock Band 4's first major update on 8th December.
The free patch is part of a post-launch program the studio said would include monthly updates of varying scope.
The first update on 8th December adds a new online competitive system called Score Challenge. This uses a live activity feed that shows players what their friends are playing, and lets them compete with each other for high scores on songs.
Also added is full combo recognition and indicator. A full combo is a perfect streak of no notes missed or additional strums/hits from start to finish. Rock Band 4 will track your full combo success when the update goes live, and an in-song indicator will let you know if you're still on track for a full combo or if you've broken your streak.
There's more on the update over at the Harmonix blog. There's no mention, however, of the hundreds of DLC tracks still missing from the European PlayStation Store. Harmonix said recently these tracks would be added in early December as part of an update. Hopefully the 8th December update announced today is what it was talking about.