There are 2 system logs available in osX
you want a quick peek at the system messages?
Now there are a bunch of byzantine options to this poorly named command, but
syslog -w -F raw
Will show you a nicely formatted and labeled set of fields and values, here, let me demonstrate by displaying Safari, as it wildly tries to copy my website pages to oddly named static pngs, I'm sure for wholesome reasons.
[Time 1305838473] [Host 8va] [Sender \[0x0-0x19019\].com.apple.Safari] [PID 846] [UID 501] [GID 20] [Level 5] [Message ImageIO: could not open '/Users/kb/Library/Caches/com.apple.Safari/Webpage Previews/.88C02C6F0DC6F52CA71726B72D215E75.jpeg-6GlG'] [ASLMessageID 3432443] [TimeNanoSec 256702000] [ReadUID 501] [Facility com.apple.console] [Session Aqua]
Now, this message is here because that directory is actually /dev/null, but Safari does not know that.