My latest article is up at www.workforce.com entitled "What are HR Certifications Worth?".  It's a compilation of some of the notes I've outlined here regarding whether certification is worth it or not.  Here's some new info on the scarcity of the certification that's changed since I talked about it here a month or two ago:

"The rarer the certification, the more it’s potentially worth. SHRM’s HR Certification Institute Web site shows that there are more than 89,000 certified professionals.  With that fact in hand, we next need a total number of HR professionals in the U.S. to determine how special the certifications make you. Here are the two numbers I considered:

The Bureau of Labor Statistics estimated that in 2004, human resources, training and labor relations managers and specialists held 820,000 jobs. I liked that number better for my rough math, since not all HR pros are SHRM members. The BLS number seems as reasonable as any I could find.

Using it, I estimate that about 11 percent of the HR professionals working across all positions and industries are PHR, SPHR or GPHR certified. That’s a big enough percentage to make people take the certifications seriously, but is also an elite enough group to make you want to be part of it."

Jump over to the article at Workforce and check it out.

Additionally, I've received quite a few emails on the topic and here's something I didn't include in the article.  The prep time to pass the class is a serious time committment, at least if you are trying to ensure you pass.  With that in mind, if you qualify to sit for the PHR and the SPHR, you should sit for the SPHR. 

While the SPHR is the tougher exam (more application-based questions, fewer questions based on pure facts), if the prep time is the same (and it is), why not get the Sr. level credentials?  If you take the PHR and pass, ultimately you'll be asking yourself in a few years whether you need the SPHR.  May as well get it all done the first time....