My husband and I were reading the paper this morning with its discussion about the new fashionistas and he was asking if I knew how "ista" came into the language. We now have fashionistas, Starbucks seems to have introduced "barista" and, I am sure, there are others.

For some reason I immediately thought it went back to the Cuban revolution of the 1950's. Of course I may think this because the revolution overthrew Batista.

Can anyone shed any light on this?

It's related to the -ist suffix which means amongst other things (1) a person who does something. physicist or (2) a follower of a school, socialist, etc. I felt the common Romance form, -ista, came in from Italian, barista, and means the person who makes espresso and similar coffee drinks. (The bar in barista is from the English bar. It's from a Greek suffix for forming agentive nouns, cf. antagōnistēs (whence English antagonist) for 'rival' (literally 'one who struggles').

Starbucks didn't introduce barista. Starbucks haven't even introduced coffee yet.

so does "barista" mean "coffee maker" or just plain old "barman" in Italy?

or just plain old "barman" in Italy?

It means the person who serves you at the bar. Bars in Italy have a slightly different meaning from those in the States. They serve coffee, other drinks, and snacks.

I'm sure I had heard of fashionistas before I was aware of baristas. But then I don't like coffee.

Here too, a 'milk bar' is (or rather used to be) a small corner shop/cafe that serves milkshakes, snacks, maybe hot chips, etc.

My guess is Sandinista since they did the overthrowing of Nicaragua in 1979 (rather than being overthrown like Batista). Sandinista! was also a 1980 album title for The Clash. I think the English usage of junta comes from this as well.

The OED1 has junta in its modern meaning from 1623. Bautista is a Spanish variant for baptist. There's also turista (M-W from 1962) and fascista (< Italian) from 1921.

I hadn't checked till now but m-w.com has
Main Entry: fash·ion·is·ta
Pronunciation: \ˌfa-shə-ˈnēs-tə\
Function: noun
Etymology: 1fashion + -ista (as in Sandinista)
Date: 1993
I think the -ista in fashionista is supposed to reflect the radical or revolutionary sense of the Sandinista National Liberation Front while others are more direct borrowings of the original equivalent to English -ist.
With my comment on junta, I meant to refer to the more recent popularity than the first usage. I think it's been in and out of style a few times over the centuries... Charles I, War of Spanish Succession, Napoleon, Sandinistas.