I'm looking for a free (preferably open source) program that will let
me draw timelines for taking history notes, preferably for linux but
windows is OK too.  I'd like it to automatically handle typesetting
and so forth.  There's a LaTeX 'timeline.sty' document class, but I
haven't figured out how to use it.

I have had the same question.  have tried ersatz methods using excel
worksheets, didn't come out so well or so easily.
Might try using MS visio.
Let me know how this comes out.