You’ve been hacked alright, I never saw a spammed login screen!
Warning: Cannot modify header information – headers already sent by (output started at /home/radio/public_html/wp-content/themes/oh-so-very/functions.php:15) in /home/radio/public_html/wp-includes/pluggable.php on line 694
It looks like there has been some meddling on the functional files (pluggable.php).
I guess you want to use FTP to install a freshly downloaded WP 2.5.1 to all files are back to what they are supposed to be. My guess (hope) is that you’ll be able to login again. Then you’ll want to change ALL your passwords (not just the WP password) and perhaps delete the theme (which might have edited files as well). I suppose this pretty much also makes you unable to find out how you were hacked, but that’ll be the least of your problems now. As soon as you’re up and running, look a little bit into the subject of “Hardening WordPress”.
The warning message above just indicates that PHP errors are displayed. If you turn off php error messages and let the header redirect happen which it cant since the header is already sent, you can see where its suppose to go.