Eclipse Version Issues

There appears to be an issue on which versions of eclipse the plugin works for. The plugin is being developed on Eclipse 3.0.0 and it appears that this is causing some issues when running on eariler versions. These problems dont appear to be source related, more to do with complilation. If exactly the same project is deployed using Eclipse 2.1.1 it works fine in Eclipse 2.1.1 environments. So i will deploy a version using Eclipse 2.1.1 occasionaly, but the main stream will stick with 3.0.0