Get Planner (binary)
Binary releases for Linux are provided by the various Linux distributions themselves.
Ubuntu users can just click here to install the Planner package
Planner 0.14.6 for Microsoft Windows:
If you feel upto it you can also build a version for Windows yourself.
The following files are available for Planner 0.14.6:
Earlier releases are also available from the Gnome FTP server.
3rd party tools
Andrew Ruthven has some tools for working with Planner. Currently they consist of a Perl script for exporting a Planner file as a CSV file.
Julien Beti developed two tools:
Planner2ICS basically transforms a planner file in an ICalendar one which can be read by ICS aware calendar application like Mozilla Sunbird, or web oriented calendar applications like PHP iCalendar.
BugzillaUpdate interfaces Planner with Bugzilla. It mainly updates Bugzilla deadlines with Planner's ones, and updates Planner percentage complete with Bugzilla ones.
MPXJ is a java tool that can read and write various formats, including Planner and Microsoft Project files.