DB Connect error when trying to install

I’m experiencing the infamous db connect error during installation.
I am self hosting.
My config file reads as follows (less the comment lines):

define ('DB_NAME', 'wordpress');       // The name of the database
define ('DB_USER', 'wpuser');          // Your MySQL username
define ('DB_PASSWORD', '*******');     // ...and password
define ('DB_HOST', 'localhost');       // 99% chance you won't need to change this value
define ('DB_CHARSET', 'utf8');
define ('DB_COLLATE', '');

$table_prefix  = 'wp_';   // Only numbers, letters, and underscores please!
define ('WPLANG', '');

I know my db is up as I can connect to the DB via the command line using the user and password stored in the config file.

SO… I took to editing the wp-db.php file to find out WHAT the db error was. Here’s what it’s returning. Here are the results:

Error establishing a database connection

This either means that the username and password information in your wp-config.php file is incorrect or we can’t contact the database server using:

wpuser/*******@localhost.

This could mean your host’s database server is down.

The db connection call returned:

Client does not support authentication protocol requested by server; consider upgrading MySQL client

I know this reads like plain english, but why would the ‘client’ not be able to connect to the database ‘serve’ when they are both on the same host???