@cr0mul3nt:
Also, if I use firefox to view http://www.pfsense.com/pfSense/xmlrpc.php I get the following error:
faultCode 103 faultString XML error: no element found at line 1
As you should, you can't just browse there.
I'm running pfSense-Full-Update-2.0-ALPHA-20091213-1418.tgz and packages work fine. There were some changes recently, it's possible if you have something older than that it won't work. Of course also make sure you have Internet connectivity from the firewall itself.