In 11.10, when I installed a desktop app it had a check box in the Software Center entry for that app to install it to the Dock right away. Sometimes I did, sometimes I didn't, depending on how much I planned on using that app.
Now in 12.04 it seems to default to jamming a new icon into the Dock, without asking me and, so far as I can tell, no way to turn it off or revert to the 'old' behavior.
Am I missing something here? Is there an easy way to turn this 'off'?