Is <SOME PROGRAM> Open Source simply because it's written in <SOME OPEN SOURCE LICENSED LANGUAGE>?

Answer:

No. While languages like PHP, Perl or Python have implementations that are licensed under Open Source licenses, that doesn't turn all code written in these languages or run under such implementations into Open Source. The code written in such languages or run under such implementations would need to be licensed under an approved Open Source license in order to be Open Source.