The new core box for Necromunda, Dark Uprising, is here.
Games Workshop published the following animated image of the box contents in the Warhammer Community:
The box is really packed, in addition to 26 minis (21 of which are brand new), extensive terrain pieces are included, as well as a new rulebook containing all current errata and FAQs. Rules for the new Uprising campaign system can also be found there.
At the same time, GW is releasing The Book of Ruin, which introduces three new gangs and many new scenarios to Necromunda.
...and then there are other nice things like Necromunda Bases, orange Necromunda Dice and extra terrain sets.