So... Kanren doesn't look like it's actively developed anymore and now folks are working on MiniKanren. The guys doing MiniKanren appear to always work in Scheme, although lots of other folks re-implement the work they publish in whatever language they're currently infatuated with.
Clojure's Core-Logic is one such project and it appears to have the most active community... but it's not really accurate to call it a faithful implementation of either Kanren or MiniKanren; rather they've used those projects as a starting point and by now they've added various other capabilities or avoided/removed others.
http://kanren.sourceforge.net/
I give a simple example of a toy use of Kanren and made a few observations about logic programming systems, here:
http://apps.keithflower.org/?p=238
Those interested will probably want to read "The Reasoned Schemer":
http://mitpress.mit.edu/books/reasoned-schemer