Currently in early private preview, SQL Server on Linux will launch mid-2017.
The announcement fits into Microsoft’s overall emphasis on hybrid deployments and their move to the cloud with Azure (where Linux is already available). The Windows version will go into general availability later this year, with a wave of launch-related events starting on Thursday. SQL Server 2016 boasts new in-memory database capabilities that can make some workloads 30-100 times faster and support for encryption for data at rest, in memory, and on the wire. It also offers analytics support using R.