The major highlight of this release is the addition of the PDO_SQLSRV driver, which adds support for PHP Data Objects (PDO). The PHP community has signaled that PDO is the future as it removes data access complexity in PHP applications by enabling developers to focus their efforts on the applications themselves rather than database-specific code.
Providing the PDO_SQLSRV driver enables popular PHP applications to use the PDO data access “style” to interoperate with Microsoft’s SQL Server database and make it easier for PHP developers to take advantage of SQL Server's proven track record and to leverage features such as SQL Server's Reporting Services and Business Intelligence capabilities. In addition to accessing SQL Server, both drivers (SQLSRV and PDO_SQLSRV) also enable PHP developers to easily connect to and use Microsoft's cloud database offering, SQL Azure, and enjoy the benefits of a reliable and scalable relational database in the cloud, as well as functionality like exposing OData feeds.
See the full blog post and details @ http://blogs.msdn.com/b/sqlphp/archive/2010/08/04/microsoft-drivers-for-php-for-sql-server-2-0-released.aspx