I was getting errors like this when one of WordPress modules was attempting to grab RSS updates:

WP HTTP Error: Could not open handle for fopen() to

After hunting around and trying to replace the Magpie RSS bits, I’m pretty confident the root cause was actually the PHP curl.so module not being enabled by default with Sun Coolstack.  This meant that it didn’t have a method with which to go grab the feeds, and after re-enabling it things were off and running again.