Probably not enough to save what is clearly a dying format (though it might have made a difference if they had done this a year or two ago), but Sony is coming out with new high-density Mini Disc format called Hi-MD that can hold up to 1GB, enough for eight hours of music. The first players which support the new format (which are said to be backwards compatible with earlier Mini Discs) should be out soon.
Read [Thanks, Troy and Kun]