При запуске в логах пишется следующее
2011/03/23 01:22:31 [info] 4784#0: Using 32768KiB of shared memory for push module in /etc/nginx/nginx.conf:3141
2011/03/23 01:22:31 [alert] 4791#0: epoll_ctl(1, 0) failed (1: Operation not permitted)
2011/03/23 01:22:31 [alert] 4791#0: failed to register channel handler while initializing push module worker (1: Operation not permitted)
2011/03/23 01:22:31 [alert] 4786#0: cache manager process 4791 exited with fatal code 2 and can not be respawn
2011/03/23 01:22:31 [alert] 4792#0: epoll_ctl(1, 0) failed (1: Operation not permitted)
2011/03/23 01:22:31 [alert] 4792#0: failed to register channel handler while initializing push module worker (1: Operation not permitted)

Настроен кэш следующим образом
proxy_cache_path /var/lib/nginx/cache levels=1:2 keys_zone=upstream_cache_zone:10m;
proxy_cache_valid 200 302 5m;
proxy_cache_valid 301 1h;
proxy_cache_valid any 1m;
proxy_cache_methods GET HEAD;
proxy_cache_key "$host$request_uri$cookie_user";
proxy_cache_bypass $http_pragma $http_authorization;
proxy_cache_min_uses 2;

Не понятно, откуда упоминание push модуля, вроде бы он у нас не используется.
nginx/0.8.54 из репозитория Debian.