I got the same problem.
Verified that allow_url_fopen = On
gethostbyname (i cant find that when i preform phpinfo)
But sice it has worked before, it should work now.
Apache/2.0.59 (Unix) DAV/2 PHP/5.1.6
Wordpress 2.8.4
Akismet 2.2.6
It’s been working until sunday… since a coupple off years.