It's not new. It's done with the registrar of the domain itself (and some registrars used to do it automatically - Netsol, for one). For instance, do "whois -h whois.crsnic.net [some nameserver]":
aura% whois -h whois.crsnic.net ns1.dreamhost.com
Whois Server Version 1.3
Domain names in the .com and .net domains can now be registered
with many different competing registrars. Go to http://www.internic.net
for detailed information.
Server Name: NS1.DREAMHOST.COM
IP Address: 220.127.116.11
Registrar: NETWORK SOLUTIONS, INC.
Whois Server: whois.networksolutions.com
Referral URL: http://www.networksolutions.com
This adds the "glue" entries at the authoritative servers for com. (so this is only needed if the nameserver is authoritative for the zone it's within - however some registrars won't let you add a nameserver if it's not registered anyway).
aura% dig +sh +norec @b.gtld-servers.net ns1.dreamhost.com