[LTParis]

I am going to be starting a new build for my TV-only HTPC, and one of the requirements of this setup is to be able to share (smb, other) from one XMBC source to another.

Can this happen? Do I need to forgo XMBC Live and jump into a Ubuntu + XMBC install instead?

[zosky]

xbmc to xbmc (live or linux on both sides) ... you should use NFS.
complete instructions for server & client side setup are on the ubuntu wiki
https://help.ubuntu.com/community/SettingUpNFSHowTo

if there's a windows box in the mix then you you'll need to go the SMB route
(again) complete instructions for both sides are on the ubuntu wiki
https://help.ubuntu.com/community/SettingUpNFSHowTo

if you want to use NFS & have an XP box -- the linux-toolkit is an option
these instructions look pretty old, but still good ( & again) in the Ubuntu community
http://ubuntuforums.org/showthread.php?t=310168

good luck