The next edition of Microsoft Office should become available during 2006.  It will offer improved security for server based documents.

Office 12 - Improved server based security on documents
http://techrepublic.com.com/2100-10877_11-5717662.html

Federal record-keeping regulations, such as Sarbanes-Oxley and HIPAA, are forcing Microsoft to examine various ways to secure Office documents. With the next version of Office, Microsoft plans to let businesses set rules, enforced by server-based software, to determine how those documents are handled

Office 12 - Some early reported info on new features
http://techrepublic.com.com/2100-10877_11-5712784.html