Latinate plurals are not a ditch I'm prepared to die in

I completely agree with this; and would go a step further. I disagree with your emphatic answer, Bean, because whilst that may be technically correct for Latin we are discussing English - and the word agenda has now been naturalised into the native tongue. Words only gain meaning by usage within a given speech community - so for me at least, agenda is a word that stands in for something like a collective noun rendering "a packet of information", and I therefore react to punctilious Latin usage as pretentious dogma! [/rant]