I gave another try to Eclipse 3.5 (Galileo) for Mac Cocoa, in the previous attempt I discovered the plugins were not working, you can read about it via the link on the bottom of this page.
There are 3 plugins that I use:
1) Google GWT and AppEngine:
2) SVN repository plugin:
3) Maven Integration for Eclipse
The installation went smoothly, all within 10 minutes.
Previous attempt to use Eclipse Galileo: