January 27, 2011.
This is no longer the newest version, version 3.1.1 is the newest.
Changes from 2.3.1 are:
Improved language support. The style settings now has a Language menu. Controls how dates are displayed. The date formatter now has additional formatting option and the localization is used from there. The number formatter now also looks at the decimal separator when formatting numbers.
Added a new option for error bars for the Bars command. The option “If<0” means that if the error column is positive the error is drawn up only, and if it is negative it is drawn down only.
When you have a label that is mapped into a value, added a way to sort the column by value. The Sort option sorts based on the string.
When a plot uses the Steps option, you can now specify a “Half step” method to connect the points.
For the Connect command, when you put a label in the middle of line, you can now select if the label is rotated with the line (old style, and stays as the default) or is always horizontal, i.e. not rotated.
The Connect command now has an “Arrows” type which puts arrows at both the start and the end of each line.
Some bug fixes and tweaks, and a couple of stability improvements.