Evidence that it's trying to improve LaTeX macro programming? It's in the documentation. Evidence that it will be released any time this century? I have none of that. It looks like the last commit to the SVN was in January.

I know some of the latex3 people, and I know they are working on it. It is not a frontend code (for example such thing as \tableofcontents), but currently purely backend stuff.

A lot of latex2e packages are using latex3 in the background (for example fontspec).