I don't know if this is a problem on Jaunty anymore, but whatever. I had to do this on 8.10 to get Eclipse to actually run and function properly.

In a word: printing. In more words: disable it.

Who prints from Eclipse anyway?

Add this as a vmarg in your eclipse.ini

-Dorg.eclipse.swt.internal.gtk.disablePrinting

The long story:

When I was at school, my Eclipse instance just would not start. Well, scratch that. A blank workspace would start fine, but a workspace that had been loaded before just wouldn't. It worked fine when I was at home. I used strace and discovered that it was trying to talk to my CUPS server. I had CUPS on my server at home for printing, and then on my laptop just had it point to that server. This worked great for printing things, but apparently Eclipse didn't like it. After searching around for a bit I found something about disabling printing in Eclipse. The result is what you see above, and this prevented Eclipse from trying to talk to the print server, and allowed it to start.