I think the way you describe the parties' ideologies is too simplistic. Nationalism is an important issue and has in fact dominated the agenda over the past term. This is despite the fact that the government was left-wing and the opposition was right-wing. In fact, the 3-party coalition was described as progressive catalanist with emphasis on the catalanist. ICV was the glue without which PSC and ERC could not be together, and ERC was the kingmaker lest time as it will be this time around.

So, the Catalan political compass, like the Basque one, has for its main axis the nationalist one, and for its secondary axis the left-right one.

On this note, given the Social Democrats' acceptance of the conventional economic wisdom, the economic left-right axis is losing importance also in Spain as a whole, and being replaced by a nationalism axis. When the economic left-right distinction between the main parties fades, "left-right" begins to refer more and more to libertarian/authoritarian.

So, on the nationalist axis we have:

• ERC: Independentist
  
• CiU: Catalanist Nationalist
  
• ICV: Catalanist Nationalist
  
• PSC: Spanish Federalist
  
• C: Catalanist Anti-nationalist
  
• PP: Spanish Nationalist Anti-catalanist

And, on the standard "political compass":

• ERC: Extreme left
  
• ICV: Left/Green
  
• PSC: Social Democrat
  
• C: Centrist
  
• CiU: Liberal + Christian Democrat coalition
  
• PP: Extreme right

I am not the first to call the PP "Extreme right" (neoliberal/neofascist), even ABC, the traditional (Monarchist) right-wing newspaper has recently done so.

CiU is part of the Europe of the Nations group in the European Parliament. Like the Basque PNV they belong in the European People's Party more than the PP, but the PP shut them out, and they may have put their nationalism ahead of their Christian Democrat/Liberal ideology. CiU represents the traditional Calalan bourgeoisie.

ERC is the Catalan equivalent of Batasuna, extreme left independentists with  past ties to violent independentism (ERC under Heribert Barrera was the political arm of Terra Lliure, which was active in the 1970's) and current ties with the squatter/anarchist movement in Barcelona. ERC has a 25-30 year lead on Batasuna in their transformation into a mainstream political party, obviously.

The PSC's mistake has been to try to out-nationalist CiU in order to attain power. They have paid dearly as people have voted for the real thing, especially after Zapatero imposed the replacement of Maragall [of 1992 olympic fame] with Montilla, though bilingual, is a charnego (immigrant from outside Catalonia).

Finally, let us not forget that the Catalan Statute was hammered out in one long Saturday by Zapatero and CiU's Artur Mas, much to the surprise of Maragall and Unio's Duran-Lleida, and to the chagrin of ERC's Carod-Rovira, who then tightened his position until Maragall was forced to throw ERC out of the 3-party government. [Note: CiU is a coalition of Christian Democrat Unio, led by Duran who is the CiU leader in the Madrid parliament and might become a minister after the next election cycle; and Liberal Convergencia which is the senior coalition partner and led by Mas and formerly by Pujol who was Catalan President for 5 consecutive terms]

Those whom the Gods wish to destroy They first make mad. -- Euripides