With ZEVO Community Edition 1.1.1 on OS X 10.8.2, sidebar behaviours seem unpredictable with ZFS volumes. Most noticeable with child file systems in the sidebar of Finder, it's possible that other apps are affected.
Also unpredictable: sidebar behaviour for an osxfusefs volume.
Some of the screen recording (2012-10-19 08-04 screen.mov) is of little interest (e.g. me dragging things into alphabetical order).
Of interest, from 08:09 on the timeline, for the last three minutes or so it's clear that volume blocky (a grandchild of volume tall):
- is sometimes classified as a CD, DVD or iPod
- sometimes does not appear when that class is shown.
(Appearance issues do affect other ZFS volumes, but the issues affecting blocky became most noticeable to me.)
Below, a screenshot from shortly after the screen recording. Note the discrepancies between:
- the sidebar of Finder
- the sidebar of the Save sheet of Terminal

I'll not rush to report a bug to Apple – I have not tested with a clean installation of the OS.
Partly related
Show child filesystems... – but in my case the startup volume does always appear properly when hard disks are shown.