Hello,
See this topic: http://forum.nginx.org/read.php?11,212439,219664#msg-219664
The described method takes care that SCRIPT_FILENAME, PATH_INFO, PATH_TRANSLATED, SCRIPT_URL, SCRIPT_URI are all set to correct values, which is especially relevant for URLs like you described: .../file.php/50/Logo_SensationalSentences_sm.gif
Andrejs