Just to add to the above response, he missed a couple of IPTC tags:
Keywords:
$iptc["2#025"][n]; (there is a list of keywords)
Caption Writer:
$iptc["2#122"][0];
Just figured I'd note it, as the keywords can be quite important for database applications. I got these by extracting IPTC tags from a Photoshop 6.0 file, so hopefully they are standardized ;)