Welcome Messages. Group and channel owners can create messages to greet new members and give them extra info.

Welcome messages are only visible to each new member – and can include media, rich formatting and more.

To add a welcome message in your group or channel, open its profile and select Edit > Welcome Message.

Buttons Inside Messages. Developers are able to put multiple buttons inside any message.

With ephemeral messages, this allows for automated flows that can run entire apps in one message.

More information for developers is available here.