mavenium is a plugin that wraps Selenium-RC in a way that should help you using this integration testing tool in your maven projects.
It provides a basic automatic parsing of the Selenium tests result file in order to integrate into maven's build life cycle, so that any integration test failure stops the cycle and your favorite continuos integration tool (sure you use one...), can warn you about that. I mean, you wouldn't need to launch these tests interactively, waiting for the Selenium tests html to be shown, hopefully full of green stuff. You don't have to provide a Selenium results parsing module in your app, either, which in fact should be unaware of the integration testing mechanism used.
mavenium works with the HTML test files generated by the Selenium-IDE firefox plugin, that lets you navigate through the webapp to be tested, defining what you expect the webapp to do really easily. Just save as many tests as you want and include them in a directory of your choice (see the parameters section to find out how). If your webapp UI changes you just have to navigate again through it and update the saved tests, that's all.
The plugin is hosted at SF.net.