sTcA:
Any chance you are using an older version of Photoshop (perhaps version for CS3?). If so, check out this section of the UPDIG site under the Web Designer heading
http://www.updig.org/guidelines/ph_metadata.html on how to update and configure CS3 to retain XMP metadata.
Under CS4 and later, the default should retain some basic metadata (like creator and copyright notice) but only as XMP metadata. You can use the pull downs in the
Save for Web (and Devices) dialogue to save even more, or no metadata at all.
If you want your images to have both IPTC and XMP, you can use the options to first save out the metadata you want with photoshop, and then configure Photo Mechanic to read in XMP and write back both XMP and IPTC. For details on the difference between these two methods of storage, see
http://www.photometadata.org/META-101-metadata-types a site which
Camerabits has provided support in the past.
David