These are the release dates of fairly recent releases (or sometimes updates, or sometimes just source-control update dates) of the Scheme implementations in (or formerly in) John Cowan's test suite. I've tried to maintain a balance between churn and stability.
|date|name|release| |2015-06-19|Sagittarius|0.6.5| |2015-06-18|Scheme 9|20150618| |2015-06-01|Picrin|(git only) |2015-05-26|IronScheme|114008| |2015-05-10|Chibi|0.7.3| |2015-05-09|Gambit|4.7.6| |2015-03-29|Foment|0.4| |2015-03-07|Larceny|0.98| |2015-02-28|Vicare|0.4d0pre1| |2015-01-16|SCM|5f2| |2014-12-02|Kawa|2.0| |2014-11-18|Chicken|4.9.0| |2014-11-??|Racket|6.1.1| |2014-07-20|Gauche|0.9.4| |2014-05-21|MIT|9.2| |2014-04-31|Scheme48|1.9.2| |2014-03-31|Bigloo|4.1a| |2014-03-20|Guile|2.0.11| |2013-05-31|FemtoLisp|20130531| |2013-04-14|TinyScheme|1.42| |2013-01-31|scsh|1.9| |2013-01-01|RScheme|0.7.3.4-b7| |2012-04-16|Dfsch|0.4| |2012-01-28|Schemik|1.2.40.0| |2012-01-09|BDC|20120109| |2012-01-08|Rep|0.90.5| |2012-01-01|Spark|20120101| |2011-12-31|STklos|1.10| |2011-12-01|Owl Lisp|0.1.6| |2011-10-01|Chez|8.4| |2011-09-08|S7|20110908| |2011-07-07|Dream|20110707 |2011-06-18|Elk|3.99.8| |2011-06-17|Mosh|0.2.7| |2011-02-02|NexJ|7.1.13.0| |2010-07-28|SigScheme|0.8.5| |2010-05-05|KSi|3.9.0| |2008-12-23|Ypsilon|0.9.6u3| |2008-06-15|Llava|20080615| |2007-02-27|SISC|1.16.6| |2006-08-12|VX|0.7| |2006-04-29|Inlab|4.108| |2006-02-04|JScheme|7.2| |2002-09-13|XLisp|3.0| |2001-10-21|Sizzle|0.0.31| |2000-12-20|SXM|1.1| |2000-01-07|Oaklisp|07-Jan-2000| |1999-10-10|Shoe|0.20.2| |1996-06-16|SIOD|3.4| |1996-01-21|UMB|3.2|