Yesterday I finally took the time to complete the ever late 0.2 release of the Project Manager IDE.
Among other things, Project Manager is now composed of a number of different things, such as the main Project Manager app, some supporting frameworks, one more app for interactive keyed archive exploring and a property list format conversion tool. To just use the IDE, all you need is the frameworks and the main app. The other two things are useful, but not directly related programs.
Since version 0.1.2, the project format has changed and Project Manager has gone through a modular restructuring process, so that most of it's functionality is now provided by dynamically loaded module bundles. I expect this to be last major change to Project Manager in the near future.
Plans for version 0.3 include full integration of the GDB debugger, project symbol indexing and CVS/SVN versioning system interaction.
I hope Project Manager 0.2 will perform to your expectations. Oh and please be sure to read the BUGS file about known problems with Project Manager - the most annoying one being opening and closing multiple projects - the GNUstep bug which causes it to crash still isn't fixed.