After much speculation and anticipation, Twitter (News - Alert) finally unveiled its #music feature. This allows users to tweet songs from popular music apps, discover new songs and emerging artists and learn more about favorite musicians. The feature is an outgrowth of Twitter’s acquisition of We Are Hunted, and positions the social networking site as a potential trend maker in the music space.

Not to be outdone, Spotify (News - Alert) has made a play for its own new feature purchasing music discovery startup Tunigo. The Swedish company will move its headquarters to New York and continue to support its existing iPhone (News - Alert) app. But now its efforts will be focused on the main Spotify app, which currently boasts 24 million users.

Spotify already has a music app, so did not need to build one from scratch the way Twitter did. But now it hopes to add the ability to help people find the kinds of songs they want to hear. This will keep ears glued to the app, and may even convince some users to switch to the for-pay version of the service.

This positions both services as rivals to Pandora (News - Alert), which has always been about discovery. Now other services are realizing how important it is to put the listener in the driver’s seat, letting him or her find the right kind of music.

The functionality is already available on Spotify, so, if you have an account, you can jump in and test it out. And, if you discover any really hot bands I don’t know about, shoot me a message, will ya?