It was promised months ago, and finally has come to Google's TV dongle: Chromecast has added support for HBO Go.

Google announced the addition on Chrome's blog, telling Chromecasters to "grab your favorite snack and get cozy on your Iron Throne, because HBO GO has added Chromecast support to their Android, iOS and web app."

Yes, that means you can cast HBO Go through all of the portals that Chromecast supports. Just make sure you have updated your Android or iOS HBO Go apps, and you can go ahead and watch those hit HBO shows like Boardwalk Empire on demand. Or Game of Thrones, as this Chromecast ad is hyping:

Oh, and you need a subscription to HBO (and thus, at least for the time being, a cable or satellite subscription as well).

Chrome's blog writer Shanna Prevé ("Head of Content Partnerships for Chromecast and Mother of Dragons in Training" - seriously) said the "Mobile and web apps will be rolling out over the next few days." So don't be upset if your HBO Go app doesn't immediately work with Chromecast - it will soon.

This is officially the seventh app to support Chromecast, and the third in a string of fall additions, after Hulu Plus and Pandora were added in October. Until the relatively late fall, Google has been slow to find partners to add cast-ability to their apps. Out of the first five apps to be available for Chrome, exactly four of them were Google apps: YouTube, Chrome browser, Google Play TV and Videos, and Google Music.

Only Netflix began with Chrome as the sole third party app supporting Google's replacement for Google TV, and that started as a three month free subscription to Netflix included with the Chromecast. That meant that the $35 HDMI TV dongle was practically free for people who were going to use Netflix whether or not they payed for it, and it resulted in the Google dongle selling completely out within days.

Google had promised that apps like HBO Go, Hulu, and Pandora would eventually be added to the Chromecast - a promise the Mountain View company has kept, although it was slow to fulfill that pledge.

Now, it seems Chromecast has picked up steam, reaching a critical mass of popular apps necessary to assure the success of a hardware platform, even if it's only $35. With Pandora radio and YouTube, for example, the Chromecast has obviated the need for separate audio hardware with streaming capabilities, if your HDTV is hooked up to a good sound system. For movies and TV, you've got Netflix, HBO Go, and Hulu Plus for a nice range of video entertainment, not to mention the random gems you can find on YouTube.

There's still room to grow and develop though. It'd be nice if Chromecast could once again make it possible for small indie apps like AllCast - which casts local media from the computer to the big screen without the need for Chrome codec compatibility - to once again develop and operate on Google's dongle. And surely more big-name third-party applications are to come on the Chromecast as well.