Try this Help-> Install New Software -> paht: http://dl.google.com/eclipse/plugin/4.2
did you try same link?
Question
I just downloaded Eclipse and the Google Plugin to begin compiling the Google Web Toolkit from the source and building a sample application with it. However, upon installation of the plugin, I am getting this error: http://i.imgur.com/9vJx3.png
From the look of the error, I'd say this might have something to do with Google actually, unless I'm missing something incredibly obvious.
Solution
Try this Help-> Install New Software -> paht: http://dl.google.com/eclipse/plugin/4.2
did you try same link?
OTHER TIPS
Are you running Eclipse as Administrator? Some of the software sources are finicky if you don't. I know I had a similar problem installing the Android Tools SDK.
I've also found these instructions from this question, if it helps.