The REST API is supposed to be release as an ad-on (extension sort of), with documentation included. I hear they are working on it. No idea when it will arrive.
@Felix, Bayron : the REsT API developer preview will be published in a few minutes, stay tuned ! We are wrapping this up in a shiny goldy red package now :)
Cheers,
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Nicolas Pastorino
Director Community - eZ
Member of the Community Project Board