The latest version of Turtle is RDF 1.1 Turtle Terse RDF Triple Language, W3C Recommendation 25 February 2014.
The documents formerly here were recorded as the http://www.w3.org/TeamSubmission/turtle/ and published as a W3C Team Submission.
The latest W3C test suite for turtle is in the RDF 1.1 testcases
Older versions of Turtle formerlly maintained here include: Turtle 2007-11-20, Turtle 2007-09-11 and Turtle 2006-12-04.
Dave Beckett, April 2015