This week, Netflix announced its US userbase grew to 31M subscribers surpassing HBO for the first time. The magnitude of Netflix’s milestone is hard to overstate. In a bid to compete with Netflix, HBO has partnered with Comcast, which serves 21M subscribers, to trial an Internet-only subscription plus HBO, the first time HBO is available to US consumers without a full cable subscription. It’s a clash of behemoths.

Separately, the NY Times revealed they have amassed more than 700,000 digital subscribers who provide upwards of 20% of circulation revenues and grow about 40% year over year. The data flatly countermands arguments against the paywall when it launched two years ago.

By my tally, the number of streaming music customers in the US is on the order of 5M. Pandora has 2.5M, Spotify has more than 1M; Apple, Google, Rdio and others likely sum to roughly the remaining million. If Spotify’s growth is any indication, the market is growing at more than 100% per year.

Across news, music and television, consumers have embraced digital subscription services. While this trend may seem like a foregone conclusion today, the jury was out as recently as 24 months ago. And subscription services are spreading.

The most recent example of this is the wave of monthly book-subscription services offered by Scribd, Oyster and 24Symbols launched in the last month or two that provide access to a huge library of books for a monthly fee. Comixology, provider of digital comic books and subscriptions, counts more than 1M users and 200M comic book downloads.

I think this is only the beginning because these models benefit both the consumers and the providers. Subscription services enable users to explore and discover. For service providers benefit from consistent revenue streams and negative working capital, two very attractive financial characteristics well established in the Software-as-a-Service market.

Excluding traditional media, there aren’t many consumer subscription services of scale today. But I suspect there is a secular change in the way people consume media that will favor more consumer subscription services in the future.