As referenced at the 2006 PASS conference this week, the Label Security Toolkit for SQL Server 2005 can be downloaded here [update: the file is attached to this post too].  This toolkit demonstrates how to combine the capabilities of SQL Server 2005 to implement a label-based row and/or cell level security framework in an application database. 

The toolkit includes a utility which allows you to logically define the security labeling scheme to be used in your app's database.  Based on this, at the click of a button the tool generates an implementation of the supporting framework.  All you need to do is create a simple view over the table(s) you wish to protect.  Support for insert/update/delete is added by writing instead-of triggers to capture these operations.  The toolkit documentation includes extensive design guidance and examples of implementing different scenarios.  Several working code samples are included as well.

The toolkit is a free download, and is not supported by Microsoft.

-Darryl (on behalf of Art)