They are backup accounts, which will explode in usage if access to centralized social media is blocked, or down for scheduled maintenance while some kind of political emergency[1] is happening in Spain.
Spain has recently reintroduced some legislation that would've made Franco proud. That said, I doubt they'll block twitter. They'll monitor it, of course -- and they'll probably use radio jamming against demonstrations.
Free, distributed (mesh-net) solutions will only help there, if they can somehow get around the jamming (relatively easy if only cell phone networks are jammed, not sure how likely it is that bluetooth/wlan will/can be jammed as well).
are you really comparing spain to iran? That seems a bit far fetched.
Even the star of this story (Barbijaputa) was suspended from twitter by the company, not by any part of the spanish government (plausibly because of misapplied ToS enforcement, not because of censorship).
[1]http://www.reuters.com/article/2009/06/16/us-iran-election-t...