Srdjan,
The whole "inflation" argument requires that reserves are maintained for spending. But apart from countries like China with huge surpluses, the main reason for large foreign currency reserves is to protect your own currency. See
http://en.wikipedia.org/wiki/Foreign_exchange_reservesFor reserve banks holding US$ the devaluation is actually good news: it's easier to support the local currency against the US$ if the US$ weakens.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1
