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)