You can add a PPA that provides a relatively current version of SmartGit(as well as SmartGitHg, the predecessor of SmartGit).
To add the PPA run:
sudo add-apt-repository ppa:eugenesan/ppa
sudo apt-get update
To install smartgit (after adding the PPA) run:
sudo apt-get install smartgit
To install smartgithg (after adding the PPA) run:
sudo apt-get install smartgithg
This should add a menu option for you
For more information, see Eugene San PPA.
This repository contains collection of customized, updated, ported and backported packages for two last LTS releases and latest pre-LTS release