If you’ve every tried to install Oracle on any UNIX/Linux system, you know what pain is — especially if all you want is the SQL*Plus client software.
Edit: This page does a better job of explaining it. (I think the page at Oracle’s site changed since I originally wrote this.)
What has also changed is that Oracle now provides the client software in its own downloadable package. You have to install a few additional libraries on Linux, but that’s not too tough.
Here’s a page that describes how to download and install SQL*Plus in a few relatively simple steps.