By default Ubuntu is blocked as its an unsupported platform. You can try running "-noplatformcheck" as part of the install command line. [ as root ] setup...eclipse... -noplatformcheck
Use "-help" to see install options.
This will skip the platform check of the installer. The down side is it also skip the required software checks so you won't get notified if any of the development libraries that eclipse required are not installed. You may also get compiler and run time issues as these are tuned to the Red Hat and SUSE platforms.