This is useful: http://office.microsoft.com/en-001/excel-help/copy-visible-cells-only-HA010244897.aspx
It didn't work for me at first, becuase I skipped critical the first step -- "select the cells that you want to copy".
I.e., I need to first select the cells, including both the visible and hidden cells. Then, I use the Go To -> Special option to essentially deselect the hidden cells.