Get ready to rock. Twitter is about to launch its long-rumored standalone music app Friday, according to a report.

The app's existence was rapidly becoming one of the worst-kept secrets in social media, especially after American Idol host Ryan Seacrest randomly tweeted about its existence earlier Thursday.

As soon as Seacrest did that, the social music startup We Are Hunted tweeted back at him — and then immediately announced it had been acquired by Twitter. (Another poorly kept secret, this acquisition likely occurred last year and was revealed by CNET last month.)

When we asked Twitter whether the app existed, they pointed us — rather meaningfully — to the We Are Hunted announcement. Now AllThingsD is reporting that the music app will launch Friday, citing sources familiar with the matter.

We Are Hunted focused on the top trending music on social media, and the Twitter Music app will likely do the same — plus suggest what other tunes you might like based on what you've listened to, and allow you to buy tracks via iTunes.

A streaming-only service, it will feature Soundcloud clips you can listen to from within the app and music videos from Vevo, according to AllThingsD. CNET previous reported that the app would be divided into four sections, including "#NowPlaying", and that a Twitter account would not be necessary to use it.

What we don't have a lot of details on is what platform the app is launching on. CNET's report said it would be iOS only; AllThingsD's sources don't specify.

Will this be one more app that Android users have to wait more months to experience? Would you download it? Let us know in the comments.

Mashable composite. Image courtesy iStockphoto, mstay