any emissions or safety related campaigns you will receive a letter about it, or can call Toyota and ask if there are any outstanding campaigns/recalls on your vehicle (call your dealer, call Toyota, etc.)
the Nav DVD campaign is more of a customer relations thing.
TSBs are just notes to the dealer techs about some notes for commonly seen/reported problems, and how to troubleshoot or fix them, or updates to the repair manuals, or info on new tools. You will not receive notice from Toyota about them (but if something becomes common enough, it might get elevated to a service campaign). Depending on your dealer, you might be able to get a copy from them.
You can find the TSBs at
http://techinfo.toyota.com/ (along with campaign info, owner's and repair manuals, training guides, wiring diagrams, etc.)
You can skim through recent TSBs here:
http://www.alldata.com/tsb/
When I can get my hands on them (usually people post them or send them to me), I've been collecting Prius TSBs here:
http://autos.groups.yahoo.com/group/toy ... iles/TSBs/
(note that in order to view files on a Yahoogroup you must be a member. you do not have to get email, though, and it's a free registration.)