Here is an interesting article on the rising costs of data breaches published in January 2010.
"The cost of a data breach increased last year to $204 per compromised customer record, according to the Ponemon Institute's annual study. The average total cost of a data breach rose from $6.65 million in 2008 to $6.75 million in 2009 ..." Read more at http://www.pcworld.com/businesscenter/article/187611/data_breaches_get_costlier.html
Dr Larry Ponemon, Chair and Founder of the Ponemon Institute notes the main causes for a data breach based on the results from 45 companies that shared their stories for the "Fifth Annual U.S. Cost of Data Breach Study," sponsored by PGP - "As part of our analysis, we try to get at the root cause of the data breach," Ponemon says. "There's negligence, where people make mistakes, such as lost laptops, accounting for 40% of the data breach cases. There are system glitches, such as a third-party sending out statements they shouldn't, which was 36%. And there are malicious and criminal attacks, at 24%."