I’ve searched for linux software a number of times to open microsoft project files and most of the information has been of the “well, I’ve never tried it variety”.
I downloaded a GanttProject 2.0.4 deb from the merlinux site here and installed it in my typical trusting fashion ( it does dump a ton of shit in /opt/ganttproject, but that’s fine as it’s really an alien’d rpm.).
I downloaded the company project file, started GanttProject and important the MPP via File->Import. Everything looks fine, took 30-40 seconds for everything to stabilize such that I could resize the window and it would adjust, but that’s probably because it’s Java and it was searching for resources to waste or whatever. So it works somewhat at least, which is more than I’ve seen anyone else say.
Hopefully someone will package it. Other than me. In true ubuntu fashion. See bug 123275.