I think it would be a good idea to give the listen skill a huge bonus if you are watching the target speaking. I eavesdrop in coffee shops all the time, and it is wicked hard to overhear shit if you aren't watching the person speak. Just saying.
Unless this already happens, in which case, kudos.
If you are guarding a person.
If that person is sitting at a table having a conversation.
You get a bonus to overhearing the conversation going on at that table.
You must be standing in order to guard someone.
As for listen, I'm not sure if that also happens.
You also get a bonus for following someone.
http://www.zalanthas.org/gdb/index.php/topic,32966.0.html
That talks about most of the changes.