“Valve Corporation has made an announcement this week that it will be implementing a major update to the Steam Library this month.”

Here.

You can read some about the library updates here.

And additional improvements here.

The new library is meant to make you more informed about your games and connected with your friends,

For developers, this gives you the opportunity to communicate and re-engage when there is things such as game update, special annoucement,challenges, tournament, and other events.

When you visit your Steam Community hub and decides to post an annoucement, you will see an interface about your event or annoucement,
These tools will be designed to help you categorize and configure any kind of communication, games, game updates, annoucements, Live Streams, challenges and other activities,

It will be easier to format the text of your descriptions, embed Youtube videos, inserting images, staging announcement and event to go live at specified date, it will let you configure broadcast settings to white-list particular accounts to Stream to your store page and event page.