This post is about the changes in the client stack for SQL Server 2012. It's a very short post. The last two major releases of SQL Server (2005 and 2008) corresponded to .NET 2.0 and .NET 3.5 SP1 respectively. In addition, each one corresponded to a new version of SNAC (SQL Native Client, that is, ODBC and OLE DB). The JDBC driver followed, but trailed a bit behind.
Newer clients have needed to be installed to support newer features. Table-valued parameters, new data types (including XML and UDTs), MARS, and filestream file access are a few features from previous (2005,2008) versions that come to mind.
SQL Server 2012 ships with a new SNAC provider/driver, named "SQL Native Client 11.0" according to the ODBC control panel applet. The new feature changes are documented in the SQL Server 2012 Books Online. In addition, .NET version 4.02 shipped just recently to add SQL Server 2012 support. There are three changes, according to the corresponding knowledge base article. The main features correspond to the Always-On functionality in SQL Server.
There are two new connection string keywords:
This can be ReadOnly or ReadWrite(default). When ReadOnly is used, applications can directly connect to a read-only secondary server, or can be automatically redirected to secondary servers in an availability group.
This keyword can be Yes or No(default). When Yes is specified, the client supports fast failover connectivity for geographically-distributed topologies through faster detection of and connection to the (currently) active server.
In addition, the .NET 4.02 supports connection to LocalDB (the standalone, local version of SQL Server used by the Visual Studio Data Tools) by the developer. Can't find any reference to this for SNAC 11, but I'd suppose LocalDB is supported with these APIs too.
One new SQL Server 2012 feature I wrote about before that I didn't find in ADO.NET 4.02 was support for the correlated server/client trace using BID tracing and XEvents. Jerome Halmans showed this in his SQLPASS summit talk and this will be supported in ADO.NET 4.5 (the version of ADO.NET that shipped as part of the Windows 8 beta). And correlated trace IS currently supported with SNAC 11.