If you program in a distributed environment, you surely are used to working with tools such as CVS or SVN, two version control systems that allow many users to work on a group of files. However, those tools don't provide for real-time updates, and if two programmers work on the same piece of code, they will need to reconcile their updates, which can be troublesome. Gobby provides group editing capability, so two or more people can edit the same document at the same time, in a collaborative fashion, with every participant getting to see all edits at the same time.
Gobby also allows you to try out "pair programming," in which two programmers share the same monitor and keyboard, alternatively working on code. In fact, you can do this with many people at different sites.