The Tekumel Sourcebook is now available from DriveThruRPG!  The Sourcebook contains a vast array of information about the world of Tekumel.  This is a reprint of the original Gamescience edition, with the addition of an index and a glossary.
Here is the Foundation blog post:
Here is the DriveThruRPG link:–Swords–Glory-Vol-1 

The Tekumel Sourcebook is now available!