Pulling security breach trends for different industries the past few months I came across a few good sources to help anyone that needs specific data.
Two sites I found with an abundance of information were:
Privacyrights.org hosts a chronological list of breaches several years back until present date with a brief description of the breach and the number of records affected.
Datalossdb.org hosts the actual breach notification letters that have been sent out.
For statistics and trends use these resources.
http://resources.mcafee.com/content/NAMcAfeeCriminologyReport (Requires Registration)
http://resources.mcafee.com/content/NAUnsecuredEconomiesReport (Requires Registration)
In general it looks like breaches frequency is about the same in 2007 and 2008. Problems seem to be related to basic items such as laptop theft, data left unencrypted, and your usual intruder attack.