This release comes just on the heels of the last but you will definitely want to upgrade--the autotracker was broken in the last one and this fixes it :-)
There are also significant improvements to the DataTool curve fitter:
--Autofitting is more robust and parameter uncertainties are automatically shown in both the plot and table. --You can choose to autofit some of the parameters while keeping others fixed.
To upgrade, click the green "Now available" button on the toolbar and choose Upgrade Now. If you don't see the green button choose Help|Check For Upgrades.
You can also download installers directly from the Tracker home page (http://physlets.org/tracker/) or ComPADRE (http://www.opensourcephysics.org/items/detail.cfm?ID=7365).