The move marks the first time a paid app has been made free for a limited time by Apple as part of its own promotion, rather than discounted by the developer directly. It's unclear how the "Editor's Choice" will differ from the "Staff Favorites" except that it appears to be limited to just two choices each for iPad and iPhone, whereas the "Staff Favorites" had at least six or more.
The "Free App of the Week" idea brings the App Store into line with iTunes' Free Single(s) of the Week and free TV and movie-related promotions (which usually consist of featurettes, extended promos and some full episodes or rentals). The iBookstore doesn't have a "Free Book of the Week" but has always had a spotlight for free books and offers free samples of nearly all books. The Mac App Store likewise has a regular section spotlighting free apps.
Apple has spotlighted the Cut the Rope: Experiments promotion on its Twitter account using the hashtag #FreeAppoftheWeek. Cut the Rope: Experiments normally sells for $1.