As of 2011,
Two parts to the driving test, the theoretical and the practical.
Eligibility for the theoretical requires a medical test (read way to skim off more money) where they check your eyesight and ask you - without any tests - if you have any issues. You then do a reflex test and you're gone.
With the theory you have the option of doing the test independently or registering (for several hundred Euros) with a driving school and then doing the classes. If you do that, they manage all the bureaucracy for you (I imagine that is a sort of kind of thing)
Or you can go indepenedent.
Fee is 89 or so Euros, and you get to stand in 3 or 4 queues to get the date of the test. I got to chose a date as close as the next week, I went for two weeks away. Be prepared that all the practice tests I found on line were in Spanish, and it is worth doing them as they are perverse double negative multiple choice questions designed to trip you up and it is worth practicing before you go.
Here in Barcelona, the test is administered in one place only (that I have found) and is done on a computer. There was a language choice of Spanish, Catalan, German, English or French. You can get extra time, but I only know that cause someone in my group had arranged it. Don't know how that's done, sorry.
The test takes 30 minutes and asks you ridiculously detailed silly questions on useless info or wildly overgeneralised silly questions, like does being drunk make you a worse driver, a better driver or make no difference at all?
Books can be bought (in BCN) in the same building on Gran Via where you book the test. Available (in ascending order of price) in Spanish, Catalan and English - other languages I didn't ask. I have heard there are complaints with the English in the exam leading to confusion. A quick glance through the English version of the book I bought looked good. I bought the Catalan as my Catalan is good enough and I wanted clear grammar in the test.
You, in theory, find out your marks the next day after noon on the Spanish transit department website, and I am waiting for mine.
I have been told, and hope to not find out, but suspect that I will, that you can take the test 2 or 3 times for the same fee, after that you have to pay again.
In another cash grab, you are obliged to do the practical test through a driving school (read several hundred Euros just to sign up plus 50 or so Euros an hour driving classes) You are not permitted to take the test until the driving instructor (who has a vested interest in keeping you in the car driving money into his pocket) says you are ready.
Cynicism meter is in the red.
More when I get further through the test process.
Further post with my personal experience.