Programmers.StackExchange.com: How can I test PHP skills in a interview?

In this recent post to the "Programmers" area of the StackExchange site, the user asks the community for help in testing a PHP developer during the interview process to asses their level of knowledge accurately.

My company needs to hire a PHP developer, but nobody has PHP knowledge in my company and we find difficult to test for PHP skills. If it were a C/Java developer I would ask him to write a quick implementation of the Game of Life, but PHP is a completely different language. I saw this test with interest. Anyone else has more suggestions?

There's several other suggestions made touching on a wide range of evaluations including:

• Security concerns (like SQL injection)
  
• Debugging/Profiling
  
• Framework experience
  
• Good overall development skills
  
• And inks to other similar questions