This is the beauty of the App Stores. The users are smart enough to decide if a free app is great or not and if a paid app is worth the money. If you are a developer and you offer a paid App, Nokia will get its cut. If your app is free then you can add it either from Ovi's channel or Maemo's Extras repository.
list new apps, or top downloads. Currently the only way to find out whats new for Maemo 5 is to visit http://maemo.org/downloads/Maemo5/ and then go download it from your phone. I am sure you agree is not that practical...