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.

Last edited by Myridon; 08/10/2008 6:18 PM.