AS has been flying these "combi" aircraft for some time - mostly within the state of AK. They now operate them on at least the SEA-ANC route as well (I believe the last flight up to ANC every night).

The "new" models are 737-400's. They have a fixed configuration starting with row 16. The retired models were 737-200's, I believe with a variable configuration (i.e. could add more or less cargo room in exchange for seats).

I haven't flown on one of the newbies yet - anyone know if they have normal overhead bins? The old ones had REALLY small bins if I remember right.