The following packages are going to be part of the main Xfce installer:
The following packages are going to be part of the Thunar installer (if there will be one):
The installer will also include some Thunar extensions.
Information about the goodies installer can be found on the goodies website.
As suggested in the Projects in xfce repos, ehm... thread on the mailing list, there should be an app installer aside from a goodies installer. It should contain the bigger projects that belong to Xfce, but are not part of the core.
Candidates are (please feel free to add to this list):