If you work in the architecture or construction industry, you will use BIM systems to model and document your designs. The IFCOpenShell addon for Blender allows you to import those files.
Paul Kotelevets explains what OpenShell does:
It is simple. This addon allows to import *.IFC files to Blender.
IFC (Industry Foundation Classes) is open interchange Building Information Modeling (BIM) format. BIM software is used in architecture and the building industry to describe the construction of buildings in their smallest details.
IFC support for Blender is important, because it is the only proper way to import correct data from such software as Archicad, Revit, Tekla and other BIM-oriented architectural software, at least, for visualisation.
The main feature of IFC (and other BIM formats) - is that it is object-oriented. So walls there represented with "wall objects", windows - with "windows objects" and so on, with set of parameters on them, such as material, density, mass, dimensions, etc.
It makes valuable sense for area of application of Blender, because BIM community is growing FAST.
About this release:
It has been a long wait since the previous official IfcOpenShell release. But now, two releases are presented at once, to make up for testing the patience of the community to this extent. On the one hand the new 0.4 release candidate improves on the stability of the 0.4 branch.
The 0.5 preview release features more bleeding-edge work. Both releases have been updated for changes in upstream projects and also include builds for the new blender 2.73 and are built using Open Cascade 6.7.1 (OCE 0.16).