>You're going to have a tough time with this one because of the differing definitions of "business day". Is Christmas a business day?

No kidding. Plus, what if the company starts implementing flextime or 4-on/3-off shifts? Or starts shipping across the International Dateline?

Hm. Microsoft Project does it somehow. The last version I looked at had a setup screen for defining what a workweek was (I think even by resource) and it had a table of holidays. So it would basically iterate through to get resource projections.

Interesting.