1. What changed?
The Museum door on the right side of the mountain in the hub has finally opened. In there you will find your personal Museum, where donated items are displayed on Armor Stands and Showcase Blocks, only visible to you. However, you can also visit other players Museums and view their items.
You can choose to donate an item to the museum by speaking to the Kurator NPC next to the entrance. That item will belong to the Museum now and can be displayed. You can take it back out of the Museum, but you will never be able to sell or trade the item ever again.
For donating a certain amount of unique items you get donation rewards. Most of them include Skyblock xp, which is a feature mentioned in the Skyblock 1.0 Design Thread, but is not implemented yet, meaning most of the rewards are actually useless. The most useful collection reward is what you get for donating 100 items: You get a Dust the Fish and unlock the Flower Minion t12 recipe.
In addition to that there is the Museum value. To determine your museum value you need to pay a one-time fee of 10m. Passing certain value thresholds will increase your Museum rank, that only unlocks better bank upgrades as of now.
2. How does that impact the game?
Certain Items might increase in price:
Rare or unobtainable cosmetic items (like Pig Mask, Happy Mask, Pioneer Pickaxe for example)
Old items (If an item is among the first 1000 ever created in the game, it gets an additional tag while on display, stating the creation number. This only takes into account items in museums, so that tag might change sometimes.)
Also in theory the museum takes lots of items out of the economy, idk how much of an impact this actually has.