While you can download the latest version of Eclipse PDT from Eclipse Download Page and install it manually, it is great to setup a repository instead so that you can get updates from it automatically via update manager. Eclipse is available in the official Debian repos but PDT is not. It is available in Yogarine Eclipse PPA in Launchpad. For Debian Squeeze, add the following line to Sources.list (or add it via Software Sources or in Third Party Repositories in Synaptic):
deb http://ppa.launchpad.net/yogarine/eclipse/ubuntu lucid main
Then execute the following command as root to add GPG keys:
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 676DBA91
Now, reload your software list:
Then, install eclipse-pdt:
apt-get install eclipse-pdt
You may not get the latest version, but the repo is constantly updated and easy to manage than to monitor and re-download the same from Eclipse download page and update.