From my experience:
Basically there are post production agencies that will do all this for you, but whether you need to use them or not really does depend on who your end client is and what format you need to deliver in. For DigiBeta I hand it over rather than renting a deck, especially as there will probably be fairly stringent requirements on what goes where (clean edit/subtitles etc). For ProRes/HDV/DVCAM I try to do it myself, but I often find that clients are not happy relying on the FCP Broadcast Safe Filter and will still want an expert to check it over. If the client has a decent enough in house production department then I just hand it over and let them deal with this which is ALWAYS the preferred method!
I don't know if it is an absolute requirement to nest the sequence or not. If I'm passing it onto an agency to sort out for me then they will normally want it done, but I've delivered tapes without nesting and no one bothered that it hadn't been done.
I've found agencies to be notoriously anal about this general procedure and if you are passing on your work for marketing by them then personally I'd want to get an expert to do it so it doesn't come back to bite you on the bum. Then again I'd far rather be shooting than doing this so perhaps I'm just making excuses not to do it 
Well that's my experience on it. Drew would probably be able to enlighten you further and let us know how you get on! 
Cheers, Simon