You wouldn't know it from the sub-rosa treatment being given to it in America, but Spain is currently experiencing something like the Arab Spring. As one Spanish author put it:
Where freedom doesn't exist it's neccesary to lose fear, it succeeded in Tunisia and Egypt, it's succeeding in Libya, Syria, and Yemen. It will succeed in more countries, Arab or not. Where there is freedom it's necessary to break the malaise, a conformity which has transformed (terrorized) citizens into consumers, some 100%.
Madrid isn't Tahrir, but the "virus" is the same: an abundance of youth without hope, doomed to a declining market modernized by cutting social rights and jobs, with the only prospect long-term trash contracts. There are thousands of stories of men and women who can't find a position, who suffer. No one speaks of them. The party line prevails, that of the others, of bureaucratese, of press conferences without questions, of the untouchables.
These forgotten tales, neglected, find resonance in social networks(Twitter: #15M; #nonosvamos, #spanishrevolution). As in Egypt: young, and not so young, mobilize themselves without organizations, without flags, without a sponsored-by, only because it is a right.
Manufacturing a Crisis
From the coverage that Spain does receive in American media, you would think that the government is one of the more deeply indebted in the EU. However, this is simply false. Eurostat data (see below) shows that Spain has a moderately high current government deficit, but has an actual sovereign debt substantially lower than France, Germany, or the UK.

So if that isn't the problem, what is?

Spain doesn't have a government debt problem. It does have an enormous private debt problem. Household debt is part of the problem, but is far overshadowed by business debt. The reason that the Spanish government faces such a premium when financing debt is that the banks doing the lending expect the government to be called upon to assume this private debt in the near future.
Spanish banking is quite neo-liberal to start with: Mortgage holders are responsible for the full amount of the loan taken. So, if their property is underwater, the difference between the amount the bank was able to sell the property for and loan amount is still owed by the borrower. But the panic isn't coming from Madrid.
Now that we know the truth about where the debt lies, we need to ask who holds it. Yes, there is a great deal of domestic exposure here: Spanish banks holding Spanish debt. But, when you look about the Merkel-Sarkozy axis of austerity, the pattern of Spanish debt holdings becomes all the more suspect.

French and German banks are heavily exposed to Spanish private debt. The Spanish government is being called upon to assuming this debt, and implement austerity measures to pay the bill, as a means for Merkel and Sarkozy to protect their nation's haute finance. It's the banksters stupid!
But it's the Spanish public paying the bill.
The Roots of Revolution
Numbers from the National Statistics Institute tell of how the crisis has played out.
Unemployment is a peculiar Spanish bane. The country regularly has a rate higher than the rest of the continent. The overall rate stands at more than 20%. The collapse of the real estate market and declines in tourism help explain this in part. More serious is the fact that much of the country has a business class intent on competing on low labor costs, even though this is out of step with the reality of modern Spain. As bad as this has been for country as a whole, the burden on young workers has been hardest. Youth unemployment in the country lies at nearly 50%.

Angry, unemployed youth are the fuel that lit the Arab Spring. And, Spain has them in spades. That shit is going sideways now doesn't seem like it should be a surprise.
Real Democracy Now!
On the 15 of May a protest was held by a group calling itself Real Democracy Now! in Madrid and other sites throughout Spain. Some of the protesters decided that they would remain the night in Plaza del Sol, Spain's equivalent of Times Square.
Although they were eventually moved out of the plaza by police, the protesters have returned to occupy the plaza until regional elections are held this coming Sunday. The opposition conservative party, PP, holds the Madrid mayor's office and the regional presidency. At first, the party greeted the protests as a sign that the Socialists, ruling at the national level, were going to be ejected from office in many regions.
That has changed. The regional government was the one that ordered the initial removal from Sol. More recently, the regional elections authority banned the protest in Madrid. As protests have popped up throughout the country, the odd situation emerged in which some were deemed legal by regional authorities and other region's argued they were an illegal attempt to influence voting. The most recent news is that the Constitutional court has ruled in favor of all protests, but I doubt this is the end of it.
It appears that something of a Spanish revolution is underway at the moment. Only time will tell how this ends.