Воопщем бяка с php-cgi.
/etc/init.d/lighttpd start
domain.com/index.php -> 500 - Internal Server Error
error.log
2010-05-14 10:47:02: (log.c.97) server started
2010-05-14 10:47:06: (mod_fastcgi.c.1768) connect failed: Permission denied on tcp:127.0.0.1:6100
2010-05-14 10:47:06: (mod_fastcgi.c.2956) backend died; we'll disable it for 5 seconds and send the request to another backend instead: reconnects: 0 load: 1
2010-05-14 10:47:12: (mod_fastcgi.c.2769) fcgi-server re-enabled: tcp:127.0.0.1:6100
если lighttpd -f /etc/lighttpd/lighttpd.conf с -D или без - все работает.