Microsoft confirm that Power BI Premium is generally available: http://bit.ly/2s9hhKN. Take a look at our earlier blog post for an overview of Power BI Premium: http://bit.ly/2qMOr4B.

Power BI Report Server is also generally available and page 32 of the June 2017 Product Terms confirms that customers with active SA on SQL Server Enterprise Core licences have rights to run Power BI Report Server.