How to use TransactionDelegate to do audit logging?

[Jeff de Vries]

I want to add a record to an audit table whenever certain objects are 
saved to the database.  Based on earlier posts, I think I need to create 
a custom TransactionDelegate, and override didCommit() (or 
willCommit()).  What I don't understand is how to access the objects 
that are going to be saved for this transaction so I can pull relevant 
information out for the audit record.  Are there any examples of doing this?

Thanks,
Jeff de Vries