To take this thought a little bit further, this could also incorporate:
* laying out files and metadata for performance characteristics of optical
media (seek times vary a lot with location, 2kb sector boundary, ...).
* compressing all files in advance may give you much better placement
options than online compression.
* This could be integrated into mkisofs in the same way that HFS support
is. Iso9660 leaves a significant amount of free space in the front, so it
may just fit.
* In a similar way, it could be done in the same way that ext3 conversion
works, but on an existing iso9660 file system to create a hybrid file
system. Bonus points for making it work with multisession writing on an
already burnt iso9660 disk.