Following up on earlier emails...
Tried going through and resetting everything-- deleted the user rows from mysql and redid the config files/usernames/passwords. Still not working-- not seeing anything added to /usr/local/virtual/, though domains and mailboxes appear as records in mysql. mail.log errors look like:

...
postfix/trivial-rewrite[17976]: warning: connect to mysql server 127.0.0.1: Can't connect to MySQL server on '127.0.0.1' (61)
postfix/trivial-rewrite[17976]: fatal: mysql:/etc/postfix/mysql_virtual_alias_maps.cf(0,lock|fold_fix): table lookup problem
postfix/smtpd[17955]: warning: problem talking to service rewrite: Unknown error: 0
postfix/master[17934]: warning: process /usr/libexec/postfix/trivial-rewrite pid 17976 exit status 1
postfix/cleanup[17964]: warning: connect to mysql server 127.0.0.1: Can't connect to MySQL server on '127.0.0.1' (61)
postfix/cleanup[17964]: warning: D24877562A: virtual_alias_maps map lookup problem for test@email.com
postfix/trivial-rewrite[17977]: warning: connect to mysql server 127.0.0.1: Can't connect to MySQL server on '127.0.0.1' (61)
postfix/trivial-rewrite[17977]: fatal: mysql:/etc/postfix/mysql_virtual_alias_maps.cf(0,lock|fold_fix): table lookup problem
postfix/pickup[17942]: 1EFF875630: uid=501 from=<my_username>
postfix/smtpd[17955]: warning: problem talking to service rewrite: Unknown error: 0
...

I tried sending an email to the box I created as suggested (see the pickup line in the). Anything else you'd advise?

Thanks again,

--Keeya

Can you connect to the database from the command line using:

mysql -u username -p database

And if that works did you compile postfix correctly with mysql support.

Check by using the command postconf -m in the response there should be an item mysql.

Yeah, everything seems to work via the command line with the reset users and passwords:

mysql -u postfix -p postfix
<entered password>
mysql>

mysql -u postfixadmin -p postfix
<entered password>
mysql>

postconf -m

btree
cidr
environ
hash
mysql
pcre
proxy
regexp
static
unix

Of note, mysql_config looks slightly different than what you had posted, though. An extra "mysql" directory, though the socket and port look fine:

mysql_config
Usage: /usr/local/mysql/bin/mysql_config [OPTIONS]
Options:
        --cflags         [-I/usr/local/mysql/include/mysql -arch ppc -isysroot /Developer/SDKs/MacOSX10.4u.sdk]
        --include        [-I/usr/local/mysql/include/mysql]
        --libs           [-L/usr/local/mysql/lib/mysql -lmysqlclient -lz -lm]
        --libs_r         [-L/usr/local/mysql/lib/mysql -lmysqlclient_r -lz -lm]
        --socket         [/tmp/mysql.sock]
        --port           [3306]
        --version        [5.0.41]
        --libmysqld-libs [-L/usr/local/mysql/lib/mysql -lmysqld -lz -lm]

Also should add the owners and perms on /usr/local/virtual for reference in case that helps:
drwxrwx--x 2 vmail postfix 68 May 23 10:39 virtual