I think the only thing that's going on is they're gearing up to compete with hard drive based units like the iPod, Archos, Jukeboxes, iRiver etc.
Previously, even if you dropped to quality to the lowest level, a mini disc could only hold a little more than 5 hours of music.
larger disc capacity + better compression = 45 hours
Sony seems to have to much invested in content to do anything that makes high quality recording and transfer easy at the consumer level.