I found some time to improve my MP3 library. Now it allows to read and write! ID3v2 Tags.
I`ve not implemented everything but you can read basic information and edit it. You can even select a jpeg or png file that will be embedded into the mp3.
You can still trim the mp3 with the timeline. ByteArray and AIR kicks ass!

Check it out here (You`ll need the Adobe AIR Runtime)

Sources will be released as soon as i find the time to clean up the code and implement some more functionality.