The upcoming version of React Router - version 4 - is more or less a complete rewrite of the current React Router (v2/v3) with some new interesting features.
Some of the major changes in the new version are:
<Match />component where ever you want to include a component according to the current URL/path
<Match>component you not only can specify a component to render but also a function that returns a component to be rendered. Using this function you can for example implement conditional rendering (like display different components if the user is logged in or not)
<Link>now can be used to render custom components instead of the standard
<a>element rendered by the current React Router version
I've shown this and other changes at the React Meetup Hamburg in a short talk.
You can find the slides of the talk: here as PDF.
To play around with RR4 I've also build a simple demo application, that you can find on GitHub.
If you have any questions, comments or feedback feel free to ping via Twitter, E-Mail or a GitHub issue.