With the newest version of AdiumX, (or even iChat) when I set my status to itunes current song, and I listen to an internet radio station, it only shows the current radio station name, not the current song name - it just says for example:
The typical format of that status message is "%_track - %_artist". There is no artist value for the radio station. If you don't like it, I suggest you set your status message to "%_track".