The Ubuntu Intrepid repository only has eclipse 3.2. I had lots of problems with that version (hanging etc) and it was ruining my programming experience. So I uninstalled it and downloaded the latest tar.gz file from the eclipse downloads page. Then I simply extracted everything under my home folder. The new path is /home/myusername/eclipse/eclipse. Brilliant. And it seemed to keep all my existing projects. The only thing was to get pydev and the pydev extensions working. For some reason this was incredibly slow but eventually it succeeded and everything was working just like I wanted. Only one thing to get. A logo for the menu item. I found an answer here: http://www.bearfruit.org/blog/2007/08/09/eclipse-svg-icons.
Here is how some other people did it (including blow by blow instructions) – http://midnight-freak.blogspot.com/2008/08/eclipse-ganymede-in-ubuntu.html.
NB there may be various things installed on my system which made it as easy to install as described. In particular, I probably had the latest java packages installed when I ran the one-step restricted updates command Ubuntu Multimedia, MS Fonts etc in One Command!.