You may have seen the ThinkForge.org platform (which basically is based on GForge). It’s our internal and external development platform, mainly for our OpenSource projects like PHProjekt, PSync from us and our friends.
I just wanted you to point at PSync, one of our flagship add-ons to our GPL licensed PHProjekt groupware. PSync is a collection of applications for synchronizing your data in your Outlook, PocketPC and Palm to and from PHProjekt. Of course the PSync tools are GPL. Up to today, we have more than 5,000 downloads of these Sync tools in total. Be aware that you need to enhance your PHProjekt installation with a SOAP backend, just consult the PHProjekt Wiki with a HOWTO for the Outlook Sync Client.