pg_dump/pg_dumpall

Greetings,
  I was just trying to get a live backup of my database and had the following error:

uselton]# pg_dumpall   > /tmp/osp5_pgsql.dump
Password:
pg_dumpall: could not connect to database "template1": FATAL:  Password authentication failed for user "root"

If it really is asking for the 'root' password I am certainly giving it correctly.  I am root as I issue the command as
well. I've tried a few other guesses at what it might _really_ be wanting (including using an explicit '-h host -p
port'),but with no better luck.  Any hints would be most appreciated. 
Cheers,
Andrew