[Orgmode] Date calculations in spreadsheet

[Ethan Ligon]

I'm working with a small spreadsheet, and would like to know how to
manage date calculations within the spreadsheet.  For example,

* How to do date calculations in a spreadsheet?
|------------------+--------------|
| Date             | Days elapsed |
|------------------+--------------|
| [2009-12-03 Thu] |              |
| [2010-12-03 Fri] |          365 |
| [2010-12-06 Mon] |            3 |
|------------------+--------------|

The question: What's the simplest way to construct a column formula for
the second column to deliver the indicated results?

And finally, my usual obligatory apology for not noticing the exhaustive
thread on exactly this topic that I've undoubtedly missed. 8^)

Thanks,
-Ethan