What's up with BIM and all the D's now-a-days???
With all the new technolgy today, many aspects of a project are brought to the forefront and considered earlier or maybe even how could the process be automated... So, there have been some additions to the 2D/3D concept.
2D - Something with 2 dimensions (flat)
3D - Something seen in 3 dimensions e.g. width, length and height.
4D - Adding the aspect of Time to a project (phasing/sequencing)
5D - Adding the aspect of Cost to a project (cost estimating)
6D - The aspect of Life Cycle Management (owner/FM)
Each of these "D's" if considered carefully can add value to a project. Software vendors have come up with creative applications to expoit these D's and as time goes on, they will become more efficient and more readily available.
Here are some examples of what's available today above and beyond Revit: (I'm not endorsing any of these, but mearly sharing a few...)
4D - Innovaya
5D - Excel, Innovaya, Timberline, US Cost, WinEst
6D - There are a few FM tools out there, but nothing with a good BIM workflow yet.