Okay, I'm assuming you are trying to install an older version that requires that package. To install that dependency, run the following commands:
wget http://mirrors.kernel.org/ubuntu/pool/universe/p/python-central/python-central_0.6.17ubuntu2_all.deb
sudo dpkg -i python-central_0.6.17ubuntu2_all.deb
Now, you should be able to install without the dependency issue.
source
Okay, since that didn't work, lets try the current version to see if that fixes the issue.
WARNING:
The following steps will delete your current radiotray configuration and possibly any files associated with the application. You should make a backup of these file before you proceed!!!
sudo apt-get update
sudo apt-get upgrade
sudo apt-get purge radiotray
sudo apt-get install radiotray=0.7.3-1ubuntu1
EDIT
Based on that bug report, you should be able to run the following to fix the issue:
sudo apt-get update
sudo apt-get install gstreamer0.10-plugins-ugly python-gst0.10 python-gtk2 python-lxml python-setuptools dh-python