NPR Music, which already offers a number of podcasts and live streaming concerts, has just launched a new 24-hour-a-day music stream called All Songs 24/7. Of course, NPR Music isn't a radio station and so doesn't have continuous programming to simulcast, so what it's doing is streaming "a non-stop mix of every song ever played during the 10 years of All Songs Considered," their regular program devoted to new music releases (and sometimes reissues).
Looking at the list of recently played songs, it seems there can be pretty jolting shifts from one tune to the next—Arcade Fire to the Preservation Hall Jazz Band to Jonsi, for example. Maybe these are the tunes they originally had permission to stream through All Songs Considered, and decided to make some further use of them, or were able to acquire the rights at a good price.
I'm not sure if this is the permanent format (or lack of format) for All Songs 24/7, or whether NPR is just putting up this mishmash of tunes to get started. Since NPR Music already has a lot of good music offerings, perhaps this is a way for them to try to make NPR Music an online music destination.
UPDATE: NPR's announcement of All Songs 24/7 indicates that the format may indeed evolve over time:
"As far as the stream goes, it might change. Maybe we’ll fill it with holiday songs, or maybe the best music of 2010 as we near the end of the year. Maybe we’ll put a concert in the stream every night or have a week where there are nothing but full concerts to hear."
