In this new post on the Northclick blog, Soenke talks about the stream wrappers included in PHP and some of the magic that can happen when they're applied correctly. In this case, it's an application of the ssh2 library (by Sara Golemon).
The new system must be very stable with a strict error checking and has to support several ways of file transports (FTP, SCP/SFTP). SCP is faster then FTP and secure by nature. It's going to be the standard way for deployment.
After finding and loading the extension, things flowed along swimmingly - the code shows a simple transfer method of transfer over a secure ftp connection, complete with a few performance stats at the end.