Unable to find the socket transport "ssl" - did you forget to enable it when you configured PHP?

Ran into this error recently... here's how to fix it, assuming you have OpenSSL already installed on your system.  For OpenSSL your PHP config values look like this:

--with-openssl[=DIR]    Include OpenSSL support (requires OpenSSL >= 0.9.6)

So, if you've compiled from scratch, you can just recompile adding this flag to your configure command.