‘Synaptic Package Manager’ tool has been dropped from the latest builds of Ubuntu 11.10 Oneiric Ocelot.
The removal of Synaptic Package Manager have been planned since the inception of the Ubuntu Software Centre. Many of the advanced features Synaptic currently provides are ear-marked for inclusion in the Ubuntu Software Centre.
Well, I really don't like SOFTWARE CENTER as it takes forever to start up and it doesn't list all packages. I mostly use Synaptic and apt-get for installing packages.
So I have installed Synaptic package from the repository.
sudo apt-get install synaptic