It looks as though (I'm going way out on a limb here...) you could do what you want by customizing
/etc/e-smith/events/actions/user-create-unix.
Find and modify the lines controlling directory creation and access rights.
You could create a custom variable named 'Ibay', define it for each user with
db accounts setprop usera Ibay group1, then add a bit to
/etc/e-smith/events/actions/user-create-unix that creates the appropriate symlink:
my $ibay = $acct->prop('Ibay') || '';
system(
"/bin/ln",
"-s", "/home/e-smith/files/users/$userName",
"/home/e-smith/files/ibays/$ibay/html/$userName"
) == 0 or die "Failed to create symlink in $ibay for $userName.\n"
warning: I just copied & adapted this chunk from S04user-create-unix; I don't understand what it does, and really suspect there should be some sort of conditional to make it do nothing if $ibay is empty...
Also,
/etc/e-smith/events/actions/user-create-unix is not a templated file -- so it is likely to be replaced, and may be modified in unexpected ways, whenever you update your SME system; maybe you should copy
/etc/e-smith/events/actions/user-create-unix to another file, customize it to *just* make the changes we're talking about, then add a link to it to the /home/e-smith/events/user-create and /home/e-smith/events/user-modify.
(The more I type, the more I think you'll want to sign on as a developer before you're done with this project...)
Or, you could go the other way and modify the ibay-create scripts to scan for all users assigned to a given ibay and create the symlinks there.
Here's a post about installing an rpm that handles ACL file rights - I think a bit more like Windows than the linux default. I don't know how well (or if) it works:
http://forums.contribs.org/index.php?topic=36092.0