I think it's too much for an hour. If they have a programming background, they'll want a simple, 'tutorial like' thing, to start writting code right away (at least thats what I wanted when I started learning perl). I'd do:

Syntax
Variables (including how to get the CGI and cookie variables)
Expressions, operators (including the werid stuff like regexp, $_, etc)
Flow control, functions
Writting and reading files and other processes
Other useful features (sending mail, mysql, maybe regexps could be here..)
Resources.

They can get into the rest of the stuff later. I'd use the PHP manual as a reference. It's very brief and clear.