Note: Anselmo mentioned in his initial report:
> Eclipse 3.7.2 (Build id: I20110613-1736) by apt-get
I would recommend to not install Eclipse from the Ubuntu repos. Please try to use an Eclipse downloaded from eclipse.org instead. Also, because Greclipse installs a 'feature patch' as Andrew mentions it needs write access to where the eclipse is installed. My guess would be that the eclipse from Ubuntu repo is installed in the assumption that a single install will be shared by all users and this will probably mean that the installation is write protected and can't be extended with feature patches by individual users.
I work on Ubuntu (but I'm a bit behind on 10.04 . But I always just download an official eclipse.org eclipse and install it in my Home directory. That typically is the setup that gives me the least amount of headache.
I'm very distrustful of the repackaged versions in the Ubuntu repos.