While you might think that the advent of subscription music services like Spotify and Rdio would cannibalize paid digital downloads from places like iTunes, for example, Warner Music Group's latest quarterly earnings report seems to indication that this isn't the case, as reported by AllThingsD. While the revenue generated by streaming services comprised 25 percent of overall digital revenue (about $54 million dollars), it didn't seem to have a negative impact on revenue from paid track downloads. Furthermore, Warner's digital music revenue appears to be increasing faster than the decline of physical media. While Warner did see some forms of digital revenue decline — like in the case of the "ringtone business" — it's nice to see digital music distribution support two paradigms in accordance with people's preferences.
Update: As All Things D notes in its update, WMG also includes money from YouTube in its streaming revenue numbers, so a large chunk of the $54 that came from streaming likely came from that service.