Version:           0.9.2-final (using KDE KDE 3.5.8)
Installed from:    Ubuntu Packages
OS:                Linux

Steps to recreate:

1. Set digikam to save tags as IPTC keywords.
2. Create new tag, say, "TESTTAG".
3. Use it to tag an image.
4. Delete the tag.

The JPEG file will still contain "TESTTAG" in its list of IPTC keywords.

Workaround: always untag an image before deleting the tag. To delete already orphaned IPTC keywords, you can recreate the tag inside digikam, then tag the image, then untag the image, then delete the tag.

Solution: When deleting a tag, Digikam should delete corresponding IPTC keywords.