While Microsoft maintains a list internally, we do not publish the company names that we federate with directly using OCS and Lync.
Matt Landis has this blog post where he is gathering that data for those interested.
Thanks Julian for the comment with other site - http://lyncdirectory.com
TomL LCSKid
Hi Tom.
There is also http://lyncdirectory.com - something of a longer list.
Regards
JB
Thanks for the pointer, Tom, much appreciated!