It's probably a test to see if it will work. If it's a disaster or failure, the EU probably won't try this again. In fact, by even trying it now they've given warning to all those with large accounts throughout Europe to pull their money NOW. So this will probably be very counter-productive, long term...
A few details on the Cyprus situation from what I've gleaned. The 'tax' hasn't taken effect YET. Cyprus is in the middle of a three day holiday, nothing can be done until Tuesday when the banks reopen. Depositors are trying to pull all their money out but bank authorities have put a 400 Euro limit on withdraws; I can't tell if that's per transaction, day, or 400 Euros, period. It doesn't matter as only ATM are available to most people right now and those have already run out of money. Some people are reportedly doing electronic transfers, but it's not easy. There's a tremendous backlash building across the island. The Greek Parliament was to vote today, Sunday, on whether to implement the tax, but it was put it off until Monday, possibly because it wouldn't have passed and the Greek President needed more time to build up support. We'll see what happens.