Not all cedar is the same, here's some info... The a.s.c (ALT.SMOKERS.CIGARS) resident expert on this topic seems to be humidor maker Daniel Morris DeRight. He responded to queries on a.s.c as well as on rec.woodworking.
"Spanish Cedar and American Aromatic Red Cedar have little in common except their appearance. Spanish cedar (Cedrela odorata) is a very mild wood with good absorption characteristics and is used to line humidors. Aromatic cedar (juniperus virginiana) is a pungent wood with varying absorption rates and is quite brittle, though workable if carefully treated.
"Spanish cedar also has little connection to Spain. Spanish cedar is grown in over a dozen countries world wide, much as English walnut is grown primarily in France and Turkey. Cuban, Brazilian, Topical American and others are all names for Spanish cedar.
"Honduran mahogany is similar to cedar in appearance and absorption, but by no means the same wood. It is used for the better cigar boxes, but most boxes are made of luann and the like."