Matt Thommes wrote that he was looking for a solution that eliminated worries about capacity (there's no upper limit on S3 storage), allow world-wide access to his music (he could connect anywhere there was Internet), and allow him to use play the music directly from iTunes. Since Jungle Disk allows you to use S3 as a remote disk, it was just a matter of dropping his iTunes library onto S3, allowing the data to transfer and then setting his new iTunes Music folder location.
Keep in mind that S3 is reasonably priced, but certainly not cheap. It costs $0.15 per month per gigabyte and $0.20 per gigabyte of data transfer. When your library starts running upwards of 30 GB, you need to do some practical math. As a rule, S3/Jungle Disk is great for backup, okay for being on the road, but not so good for day-to-day use on your main computer because you're paying for that transfer. Do keep in mind, though, that Jungle Disk does some caching. On the other hand, if you're bringing a laptop with you, odds are that you can just store your data right on the laptop and use S3 as an emergency backup.