Unfortunately on OSX you're stuck with the BSD
netstat which will not show you the process ID that is attached to a given port. What you have to do instead is use
lsof. The syntax you'll need to use is:
lsof -i :8080
This will print out gobs of information, most of which you don't care about, but the fields are well labeled. For example, check out this example output.
lsof -i :53237
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
GoogleTal 927 guest 29u IPv4 0x2c3f7f95244855c3 0t0 TCP localhost:53237 (LISTEN)
This tells me that port 53237 is in use by process ID 927. When reading the COMMAND field keep in mind that this output is truncated, in reality the full name of the binary is GoogleTalkPlugin.