I would like to implement Row-Level Security in our software, which is already using Hibernate 3. I could not find any documentation on the subject of Row-Level Security in Hibernate. Is there any way at all to do this in Hibernate?

It depends what exactyl you mean by row level security.

Check out this link:
http://www.hibernate.org/hib_docs/core/ ... e/#filters

You actually might want to do this right at the database level, as opposed to the application level. Get your database admins involved!