The most recent version of DataGraph is 2.2.3
The sub-pages detail the changes made.
2.0 - May 3rd 2009. No release notes here. After this version, updates and release notes are described using the web site.
2.0.1 - June 1st 2009.
Improved Arbitrary fit, more fill options for the Plot command, more...
2.1 - October 25th 2009.
Magnify command, more fill options, improved eps/pdf export, more...
2.2 - April 18th 2010
Main change was the new Connect command, search functionality and the ability to draw multi-line text everywhere more...
Latest update is 2.2.3, released May 4th 2010.
And then there is the bleeding edge - the beta version.