By the way I know the bought a company in Poland and so they use their account and so on. But does someone know what are their advantage to stay there? Because usually "brokers" (or similar) use some kind of fiscal paradise like Chypre eg.
AFAIK there is only one advantages with Poland and some other countries: Bank transfers are final. The bank won't return an incoming transfer unless MtGox agree.
Besides from that, it just happend to be where they finally found a bank willing to deal with a Bitcoin exchange, after their French bank threw them out. They don't get very good terms at the Polish bank, but what can they do? Not many banks in Europe are willing to do business with a Bitcoin exchange.
The other strategy (bitcoin.de and Bitcoin-Central) is to let each customer effectively have their own bank account tied directly to their exchange account. We have yet to see how this works out. It will probably be difficult for Non-EU citizens to get accounts there.
THis is simply not true. I currently have a incoming Polish payment to my Polish account and it was fraudulent, so they are in the process of reversing it.