We mentioned this thought in passing alongside Dieter's report on the Nokia
App Ovi Store, which he says has far, far better discoverability than the iTunes App Store:
What Nokia has done is build a sophisticated relevancy engine that can sort apps based on a variety of factors that are actually relevant to you — like what you friends are using, or what kind of app you like to download, or what music you tend to prefer. It looks to be much better than your standard “top 50″ list
Sure, the automagical playlist generation part of Genius wouldn't be necessary, but the part of Genius that scans your collection, anonymously uploads its metadata to the cloud, and then compares it with everyone else in the massive ecosystem in order to crowd source recommendations... that could help discoverability immensely. It could give us great apps that go great together, in Apple-speak.
Of course, Apple also has to crack down on short-sighted developers trying to game the search results, but Genius recommendations could go a long way towards cutting through the glut that 20,000+ apps brings with it. What think you?