As expected, Spotify has just announced that for the first time, the company will offer free mobile streaming.

Until today, Spotify users who chose the free, ad-supported option were banned from any sort of mobile listening. Zero. Zilch. Today, Spotify is opening it up a bit for smartphones and pretty much all the way on tablets.

“Today we’re giving people the best free music experience in the history of the smartphone and the tablet,” said Daniel Ek, CEO & Founder at Spotify. “Whether you’re going to the gym, or having a party with friends. Just sit back and let Spotify serve you great music for every moment of your life.”

Ok, so here’s the rundown: Free users now have access to streaming music on their smartphones, but it’s limited. You can listen to playlists (either personally curated or from users you follow) and you can “shuffle” through artists’ entire catalogs.

“Want to listen to a certain artist? Just hit shuffle play, sit back and listen to their entire catalogue. Don’t settle for something similar. Don’t settle for just one track from the artist you want to hear every 20 minutes,” says Spotify in a clear “shots fired” statement aimed at the likes of Pandora.

What’s obviously missing from Spotify’s free features for smartphones is the ability to search for and listen to any song you want at any time. I’m working on getting a statement from Spotify on how many “skips” free users will have in the “shuffle” mode and will let you know when I find out.

When it comes to tablets, Spotify is breaking it wide open. iOS and Android tablet users can now stream any song they want for free.

Here’s Spotify’s justification for the difference in smartphone and tablet streaming:

“Unlike mobile devices, it turns out that tablets are becoming the new desktops. Tablets are where people lean in, search and build playlists.”

Of course, it’s likely that Spotify simply had a hard time negotiating with labels and were unable to bring full, free streaming capabilities to smartphones. That, and maybe they didn’t want to give all the milk away for free – they still want users to buy the cow. Most likely some combination of the two.

If this is a bit confusing, here’s a handy chart:

Spotify also added 20 new markets today, which is pretty big news on its own. As of today, Spotify is available in the following 55 locales:

Andorra, Austria, Belgium, Bolivia, Bulgaria, Denmark, Cyprus, Czech Republic, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, Monaco, The Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland, Turkey, UK, Argentina, Chile, Colombia, Costa Rica, Dominican Republic, Ecuador, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Uruguay, USA, Australia, New Zealand, Hong Kong, Malaysia, Singapore and Taiwan

Spotify has just over 24 million total users, 6 million of which pay for the service. Today’s announcement will likely excite the 18 million-or-so Spotify users who are still hanging out in free land. Not allowing any sort of mobile streaming put Spotify in the dark ages, when compared to most other music streaming platforms. With today’s announcement, Spotify moves into the mobile age while still giving users a reason to pony up for a monthly subscription – mainly better music quality, unlimited smartphone streaming, offline mode, and the removal of ads.

Oh yeah, and they also added the entire Led Zeppelin catalog – so make sure you throw all of that on a playlist for mobile streaming.

Images via Björn Olsson, Flickr and Spotify