Does the latest version of d3 on Linux support CD burners? Ideally, the CD
drive should be used like any other tape device (set-device, t-att...).

This would be an issue with Linux rather than D3 - if your burning
software allows you to simply write a file to a mounted CD volume, then
you are away, if not then you may need to look at alternatives like
having your backups written to a Linux directory as normal, then
kicking off another process to do th actual burning (copying all files
from you backup directory)

I'd suggest using compressed volumes on the D3 side - that way you can
fit 2-3Gb of 'D3 data' onto a 700Mb CD.

We also have a few people that are using USB connected drives for
backups. We are about to adopt internally as we are backuping up around
70Gb ad I'm getting sick of changing 40Gb tapes :-)

If I could fit everything down to 1Gb, I'd probably have a serious look
at a 'thumb drive' style device