There is a huge privacy issue in the Cloud. Some progress has been made with Homomorpohic encryption, but its still some time away.
http://en.wikipedia.org/wiki/Homomorphic_encryption http://blogs.teamb.com/craigstuntz/2010/03/18/38566/
http://en.wikipedia.org/wiki/Homomorphic_encryption http://blogs.teamb.com/craigstuntz/2010/03/18/38566/