The Office Team has a summary blog post about announcements at Build 2017.
- New and Updated Microsoft Authentication Library (MSAL) Previews
- SharePoint Framework Extensions (modern equivalents for Custom Actions, Field JSLink rendering and ribbon extensions)
- SharePoint sites API is now in the Microsoft Graph v1.0 endpoint
- Microsoft Teams APIs are now in the Microsoft Graph beta endpoint
- Webhooks for Azure AD Users and Groups
I am as excited as ever as a developer/consultant in the SharePoint/Office 365 eco-system!