FWIW – I just downgraded from PHP 5.5 to PHP 5.4 and it works again. Not sure what is causing the incompatibility however, other than the errors posted above.
Curious if you had any more luck with this? I am having the same problem, but with CentOS 5.10, Nginx 1.6, and spawn-fcgi. The site will sometimes work, and sometimes not. Removing the buddypress folder from the plugins directory will cause the site to start loading again, but putting it back breaks it. The only errors are: