There are some small experiments on Codepen implementing/experimenting individual features. Once there's a good bunch of such implementations to refer/compare, people will probably start compiling them into a bootstrap theme.<p><a href="http://codepen.io/search?q=google+material&limit=all&depth=everything&show_forks=false" rel="nofollow">http://codepen.io/search?q=google+material&limit=all&depth=e...</a>
I am working on a Bootswatch theme called Paper, which is based on Material Design: <a href="https://github.com/nicolasmccurdy/bootswatch/tree/gh-pages/paper" rel="nofollow">https://github.com/nicolasmccurdy/bootswatch/tree/gh-pages/p...</a><p>I have a bit of work to do before it will be done, but if you'd like to contribute feel free to fork it.