No, we're working on a v1.0 release
You can see the latest code here: https://github.com/lhorie/mithril.js/tree/rewrite
The main highlights are improved performance, modularity and API design. The `render` module - which is analogous to React/Preact - is about 3kb min+gzip and has support for fragments, lifecycle hooks for animations among other things.
Other additions to the framework include new utilities for testing, bundling, and optional reactive streams.
It's currently in release candidate status, but there are already some applications in the wild using this new version. I'm just finishing up writing documentation before the official release