Can you give me some info on exactly what is not working? What is the error you are getting? I just tested with Joomla! 1.0.9 and all seems well. Be sure to check out the FAQ section for a couple things to check on the new site, specifically the one dealing with the correct permission settings.
Matt, can you PM me with your site address and a valid account so I can check it out here? Is this site hosted on the same server that your other working sites are hosted on? Also if you could include the name of the hosting company so I can read through their FAQs to see if they are blocking scripts or something.
Matt, Sorry, I did look into the problem. Looks like it is somehow blocked on the webserver. Appears they are overally security cautious and have blocked alot of the remote communications stuff. None of the simple functions are even being executed or they are and the xmlrpc response from the host to Blogg-X is being cut off. I have checked you php and mysql versions and and all is compatible. I would talk with the webhost but after reading some stuff on the forums it doesn't appear that they like to change the security settings.