From the Rdio blog:
Hot on the heels of our Stations launch, we’ve built Recommendations as another great means of effortless music discovery. Powered by technology from The Echo Nest, the new feature provides a steady stream of new music recommendations — including albums, stations, and playlists — based on what you listen to most and who you’re following.
I’ve long wished for Rdio Recommendations to come back, as I think they used to a great way to find new music in the Rdio 1.0 days. Rdio has changed in the past two years, and the need for Recommendations was partially obviated by Your FM and stations. However, I’m looking forward to seeing if the dedicated section will be as good as the original one used to be – particularly in how it should recommend entire albums and stations.
According to Rdio, Recommendations will be added to the iOS app “soon” – hopefully alongside an update for iOS 7.