I remember seeing in the Q&A tweet post that someone asked what the buildings were going to be like and I'm pretty sure you will be able to rent apartments. I'll have to go find it again and look over it to make sure.
I believe this is the quote you were talking about:
GameGuru: Fun – an integral part of the night life of any big city. Does this mean that Simville become a metropolis in The Sims 3 Late Night EP? Can your sims change their cozy houses to modern city apartments?
Grant Rodiek: Yes! Trust ready to come off your last night! Cozy cabins and cottages still remain, but also you can choose a city apartment flats or even penthouse!
Please note that this version has been translated from Russian, hence the awkward syntax. Still, it seems pretty clear that we definitely will be renting apartments!
If that isn't your source, Sushi, please share what you were thinking about!
Edit: forgot to mention, in that article, because of awkward translation, they refer to Sims as your "Trust". I'm assuming it's the closest English translation to a Russian phrase indicating a guardian-charge relationship.