There where 2 main changes:

The introduction of a proposal system called the SPS (Steem Proposal System) or Steem DAO. It is similar to the worker proposal system in Bitshares. Basically anyone can propose a project and request funding if enough stakeholders support it by voting on the proposal. You can find the proposed projects on either one of these frontends:

• https://steempeak.com/me/proposals
• https://steemproposals.com/
• https://steemitwallet.com/proposals

The funding for the Steem Dao SPS comes from reducing the reward pool from 75% of the inflation to 65%. The approved projects are paid in steem dollars.

The EIP (economic improvement proposal) that introduced 3 changes:

• The return to the 50/50 payout on posts between authors and curators (instead of 75/25).
• The introduction of a separate downvote pool. Each account gets 2.5 "free" downvotes per day. This was introduced to help stakeholders combat "abuse" without having to waste voting power.
• The author rewards where changed from linear to superlinear linear convergent. Basically the votes are non-linear below a certain threshold. After that the payouts are linear again. This was introduced to help combat the milking of the rewards with small paying spam posts.

In addition the curation rewards reverse auction was changed from 15 minutes to 5 minutes.