Hello Sean,

> 
> In my experience alone, i have found that i cannot delegate, 
> for example, a something.biz domain to an 
> ns1.somethingelse.com.au and ns2.somethingelse.com.au unless 
> i make glue records for ns1.somethingelse.com.au and 
> ns2.somethingelse.com.au
> 

You may be confusing "glue" records with "host" records.

In EPP protocol based registries (including .com.au, .org, .biz, .info),
there are separate data records for domains, hosts, and contact records.
To delegate a domain name to a nameserver, requires the existance of the
host record for that domain name in the registry.  HOWEVER this registry
host record does not need to contain the IP address (and in most cases
SHOULDN'T contain the IP address).

So if you create the domain something.biz, and wish to delegate it to
ns1.somethingelse.com.au and ns2.somethingelse.com.au, you should first
create the "host" records for ns1.somethingelse.com.au and
ns2.somethingelse.com.au in the registry WITHOUT the IP addresses.  If
you create these nameservers without IP addresses, the registry WILL NOT
create a glue record for them in the zonefile.  Leave it to the .com.au
zonefile to manage the resolution of ns1.somethingelse.com.au to an IP
address.

If you create glue records in a .biz zone for a .com.au domain name you
potentially create inconsistencies between what the .com.au zonefile has
and the .biz zonefile.  Thus generally it is not a good idea to create
glue records for .com.au nameservers outside of the .com.au zonefile.

In the case of the .com zonefile, it is better not to have glue records
for .com.au nameservers.

Regards,
Bruce