Power BI dataflows have been available in public preview since November 2018. For almost five months, customers around the world have been kicking the tires, testing and providing feedback, and building production capabilities using dataflows.
When Microsoft published the latest Business Applications Release Notes, the “new and planned features” list included dataflows general availability with a target date of April 2019, which could typically mean anything before May 1st.
But… April has just arrived, and so has the dataflows GA!
The full details are on the official Power BI blog, so be sure to check it out. Also keep in mind that although dataflows are now generally available, some specific capabilities are still in preview.