PHP is supplied under an open source license. I'm not sure why you're asking what he means.
At the risk of sounding pedantic, that's not right. It's released under the PHP License... which does have some restrictions.

AJAX isn't a language, it's a grouping of technologies (it's not even new... the capabilites have been around for some time.)

I'm not sure what duality samba is referring to, but ok.

I'm not wholy convinced flash is a language either, Java is... as is JavaScript, as is ActiveScript, and so is VBScript.

.NET is a technology. VB.NET and C# are the language-specific implementations of that technology.

-tg