The user and all related content has been deleted.

I am not seeing this. Can you provide some details? Zenphoto release, maybe a link to the site.

But just a warning. Since searching uses the `&` for an AND operator, use in tags may be a bit problematic for people doing a search--they will have to enclose that tag in quotations.

The user and all related content has been deleted.

do you mean this:
`<meta name="keywords" content="architecture, architektur, berlin, black, black & white, colors, farben, formen, fotografie, galerie, gallery, landscapes, landschaft, new york, photography, robert strauch, schwarzweiß, shapes, stadt, stadtansichten, urban, white" />`?

That has the properly encoded ampersand.

The user and all related content has been deleted.

Yes, that is correct. See: http://www.w3schools.com/HTML/html_entities.asp