If you get the following error:

/etc/ldap/slapd.conf: line 127: substr index of attribute "sambaSID" disallowed

when you run slapindex, then you haven’t updated your
samba.schema to the version from Samba 3.0.23. Dapper and Edgy
had 3.0.22, so if you’ve recently upgraded to Hardy, you will see this
problem. The file should have an MD5 of
0e23b3ad05cd2b38a302fe61c921f300. I’m hoping this resolves
problems I have with samba not picking up group membership changes. I’ll
update if it does.

Update: Having installed the new schema and run slapindex, net rpc info shows I have twelve groups when previously it showed zero. This may not solve my group membership problems, but it can’t be a step backwards.