Bloomberg News reports:
About 1,780 expatriates gave up their nationality at U.S. embassies last year, up from 235 in 2008, according to Andy Sundberg, secretary of Geneva's Overseas American Academy, citing figures from the government's Federal Register. The embassy in Bern, the Swiss capital, redeployed staff to clear a backlog as Americans queued to relinquish their passports....
During a 10-minute renunciation ceremony in a booth with bullet-proof glass windows, embassy staff ask exiting Americans whether they are acting voluntarily and understand the implications of giving up their passports. They pay a fee of $450 to renounce and may incur an "exit tax" on unrealized capital gains if their assets exceed $2 million or their average annual U.S. tax bill is more than $151,000 during the past five years.
They receive a certificate within three months, telling them they are no longer American citizens and entitled to the services and protection of the U.S. government.
The way the Bloomberg article frames the news is that "Rich Americans renouncing U.S. citizenship rose sevenfold since UBS AG (UBSN) whistle-blower Bradley Birkenfeld triggered a crackdown on tax evasion four years ago," but it seems to me there was some other newsworthy event that happened in 2008 — maybe an election? — that also might have had something to do with it.