6.2 -> 6.4 snapshot

Greetings...
Having finally gotten an upgrade to the web server hardware here,
I've installed 6.4 on the new system and want to dump over the first
database I've chosen to migrate. The old system is the release
version of 6.2. I did a pg_dump of the database with the 6.2 version
of pg_dump, but got errors when I tried to load it into 6.4 on the new
system. So, I figured I should do both the dump and the load with the
6.4 version of pg_dump. When I try, however, I get the following
message:
Connection to database 'rrc' failed.
Failed to authenticate client as Postgres user 'postgres'
using <unknown authentication type>: be_recvauth:
unrecognized message type: 131072
This is with the Oct. 11 snapshot. Any suggestions on how to
proceed? TIA...

-Brandon :)