I mailed a DVD back to Netflix on Friday and was surprised to get emails reporting it had been received and a new DVD mailed on Saturday. Previously Netflix in my area had worked on a 5 day week basis. Apparently Netflix started experimenting with Saturday processing back in January.
It is not immediately clear to me why they are doing this, it seems to increase their labor costs substantially for a somewhat modest service benefit. Perhaps as speculated in the comments in the link above they were having trouble handing the workload on Mondays and are trying to spread out the load a bit.
Of course this will become moot if the post office ever eliminates Saturday delivery.