While debating the pronunciation of Eyjafjallajökull has been all the rage in the blogosphere (see here), a more ominous threat has emerged, the eminent reuption of the great and powerful Katla! ...yeah, my reaction too. Somehow, the pronunciation difficulty of Eyjafjallajökull added to its pop cultural caché. I fear Katla, regardless of the might of its wrath, will suffer a sort of pop cultural Marsha Marsha Marsha syndrome.
For what it's worth (not much), Wikipedia's pronunciation is here.