It appears that US based Internet radio stations are prohibited from certain activities:
1. Playing more than two songs in a row from the same album within three hours.
2. Playing more than three songs from the same album within three hours.
3. Playing more than three songs in a row from the same artist (or anthology).
4. Playing more four songs from the same artist (or anthology) within three hours.
5. Pre-announcing (e.g. program guides) a particular song or playlist order.
6. Playing any request song within an hour of its request, or playing any request song at a specific time.
Although onerous, complying with (5) and (6) is pretty simple. However, complying with (1) through (4) is a potential scheduling nightmare. For instance, if I have a limited number of 'Country' artists and use a smartlist to rotate through various genres, it is possible that the shows might violate one or more of the restrictions.