OGG4iPhone got a massive update, not does it only play OGG files as before, it also plays MP3 now 🙂

Changes:

MP3 support added. ogg4iphone now plays MP3s in addition to OGG.
Playlists added. Add music to two playlists available. This feature will be worked on much more.
Stop music button added. Enjoy the silence. 🙂
Random play added in the Settings.
Volume increased 3x. Now you can hear the music too!
Tons of bugs fixed.

Thanks to ZodTTD, the author himself, for the news.

http://www.zodttd.com/forums/showthread.php?t=1963