We're definitely going to add math support to GitHub markdown.

Is there a timeline for adding math support to GH markdown?

I've had to resort to human-side rendering to put LaTeX/math in a GitHub flavored markdown file.

github being a social network is the main reason of its success.

Is it? Networking yes, social maybe?

I don't have any memories of early GitHub but did any of it's competitors come close to being as good?

I'd rather that they supported a standard like MathML or LaTeX.

There was someone working on LaTeX support a few years ago, but iirc it was very difficult to secure it enough to feel comfortable letting it run server-side for rendering. Source: I worked there when they were working on it.

What about client side rendering via MathJax? You could have your LaTeX code embedded in your markdown and MathJax could substitute it for appropriately rendered symbols as necessary.