You'll see ads if you're:
-Not logged in
-Visiting a journal whose user chose to use "Sponsored+" class (and you're a free user)
-Logged in as a "Sponsored+" user.
Paid and Permanent users don't see ads. Ever. ^.^v
It's actually not too bad, I guess, with 1 GB of photo hosting space, in exchange for ads....
It's interesting though - if paid users will never see ads on "Sponsored+" journals, how will that affect the layout? I guess the place where the ads would be would just be blank...
Kinda sucks that logged out users will have to see ads though... and the fact that I won't be able to boast that LJ is ad-free. Oh well.
Here's the news post: http://news.livejournal.com/91919.html