An interesting article about IRS initiatives in Switzerland:http://www.bloomberg.com/news/2011-10-24/swiss-banks-said-ready-to-pay-billions-disclose-customer-names.html

For U.S. citizens who have an aggregate of $10,000 or more in foreign bank accounts, there is a requirement to disclose this information to the IRS, by filing an FBAR with the Department of Treasury.