I am very very pissed off.
IMSLP has helped me with sheet music scores for the past year. Its method of scanning and publishing public domain music helps to spread the art that is music to people who cannot afford expensive public editions.
Universal Edition's actions are shameful. They reinforce my opinion that copyright law should not exist, or that it should be extremely short term - one year, for example.
The service IMSLP provides is one that spreads musical art and voluntary cooperation. It would not encroach upon publisher's profits in the least - there are always going to be significant numbers of people willing to pay for quality music. IMSLP is not always Weiner Urtext and people realize that. But it helps out broke musicians who can't necessarily pay $100 for the Beethoven Sonatas.
What assholes. May their publishing houses burn to the ground.