I'm using Safari 5.1.3 on Lion.
Each time I click the RSS icon in the address bar (or directly visit the feed), Safari will report can't open page, saying operation not permitted with the
NSPOSIXErrorDomain: 1 error. For other web sites, Safari works fine.
I have no 3rd party firewall installed on my system. I also tried to disable the firewall in system settings but still getting the same error.
As I use Google Reader, I've once installed the "Add To Google Reader" extension from Apple's site, but it didn't work for me.