The core Songbird player’s shuffle feature only shuffles songs. Album purists who still want a little bit of randomness in their life can use the Category Shuffle add-on to queue up random albums and shuffle using the album as a unit. The add-on simply grabs a random album, plays every track in order, then moves on to the next random album.
The album isn’t the only unit that Category Shuffle can shuffle. It shuffles by artist, composer, genre, rating, or release year.