Yahoo announced today its own, subscription based, online music store. Subscriptions are starting at $4.99/mo for a one year subscription or $6.99 on a month-to-month basis. The subscription gives access to a library of more than one million songs.

Yahoo's subscription service is based on Microsoft's Janus technology, allowing subscribers of the music store to transfer their music on a plethora of MP3 players, but not the iPod, which does not support Microsoft's DRM technology.

Apple's shares (AAPL) plummeted -7% after the announcement, but recovered to 2.22% lower before the markets closed. Other online music market players closed significally lower. Napster (NAPS) fell 32% to $4.32 while Real Networks (RNWK) fell more than 21% to $5.79. Yahoo's shares (YHOO) closed 2.41% up to $34.88.

Analysts tend to believe Apple should not be threatened by Yahoo's announcements though. Piper Jaffray's Gene Munster even qualified the stock as a buying opportunity.