A bug report has been lodged.
The bugged version is git20120229 compiled April 7 2012 and is currently in the XBMC PPA.
You can check your verison of XBMC on the System->System Info screen within XBMC.
The offending version is shown as;
"XBMC 11.0 Git:Unknown (Compiled : Apr 7 2012)"
You can wait for a fix to come down the pipeline, or if you are impatient (like me) you can revert to the older version.
You will need to download these files;
Next, uninstall the bugged version;
sudo apt-get remove xbmc
Now, install the previous XBMC release from the files you downloaded;
sudo dpkg -i xbmc-bin_11.0~git20120321.14feb09-0ubuntu1~ppa1~oneiric_amd64.deb
sudo dpkg -i xbmc_11.0~git20120321.14feb09-0ubuntu1~ppa1~oneiric_all.deb
Now, you should be able to scrape TMDB without connection issues.