Microsoft released the developer preview for SharePoint Framework.
It’s all in Github now – https://github.com/SharePoint/sp-dev-docs/wiki
If you are new to this, watch the official Microsoft statement to get some heads up – https://blogs.office.com/2016/05/04/the-sharepoint-framework-an-open-and-connected-platform/
Also note that SharePoint Framework web parts are not supported for production use yet.
So just be ready guys !!!