WebSphere is a generic IBM product name that refers to a number of different things generically related to Java J2EE development.
WebSphere Studio
IBM's IDE for developing J2EE code. This is just Eclipse with some proprietary plugins. WebSphere Studio 5.1.2 is based on Eclipse 2.1.3 and contains all the bugs of this old version, such as lack of printing support under Linux.
It encourages breaking up J2EE projects into a bunch of project pieces, which makes configuration management much more work and more error-prone.