In my opinion PHP should not be included in a front-end designers skillset...That is for the back-end developers...

I frequently do job searches to check what's out there and I typically find that front-end developer skillsets include XHTML, CSS, JavaScript, and PHP (or some kind of server-side language). Companies usually also want a person to be familliar with a graphics editing program such as Photoshop or Fireworks. SEO skills are also a bonus.

Besides the basics of CSS/HTML and graphics editing software, as a front-end developer you are also going to be forced to deal with mobile site design and development at some point. Solid working knowledge of at least one JavaScript library is also a bonus, along with any UI insight, and obviously the knowledge of browser compatibility.

A front-end developer needs to be able to translate a graphic web design into standards compliant code ("PSD to HTML"). But, there's a whole lot more to know as well and you only learn it through much hard work and years of experience.