Successful Microsoft SQL Server Support for PHP on Linux

I recently had a requirement to enable a PHP application on Linux servers to connect to a remote Microsoft SQL Server database. Despite initial concerns that this was impossible or at least very difficult, compounded by numerous confused forum/blog posts suggesting it to be so, it turns out to be eminently achievable.

Unfortunately, there seems to be a lot of misinformation out there, so at the risk of adding to it, here's my writeup of getting PHP on Linux to talk to an MS SQL Server database, using both the mssql_* functions and the Zend_Db component of Zend Framework.