DNSSEC allows you to go from dns name -> CERT in a secure
manner. The application then checks that the cert used to
establish the ssl session is one from the CERT RRset.
Basically when you pay your $70 or whatever for the CERT
record you are asking the CA to assert that you have the
right to use the domain name. It's expensive because they
are not part of existing DNS trust relationship setup when
the domain was delegated in the first place.
The natural place to look for DNS trust is in the DNS.
Mark