This next rather long article answers the question, 'So how do I write a synopsis for a non-fiction book?' and gives several actual examples of both good and bad synopses: http://www.annemini.com/?cat=337. For those who read all the way through there are enough dollops of humour along the way to keep you reading. Some of the excellent advice goes like this:
(a) regardless of the tense of the manuscript, the synopsis should be in the present tense, and
(b) even if the manuscript is written in the first person, the synopsis should be written in the third person, UNLESS
(c) the manuscript being synopsized is a memoir, in which case the synopsis should be written in the past tense and the first person.