<p>We are setting up a <a href="http://selenium.openqa.org/" rel="nofollow noreferrer">Selenium</a> test campaign on a big web application.
The first thing we've done was to build a framework which initialize SQL data in database before the test, launch the test, archive results and then clear data.</p>

<p>We've integrate that in a Maven 2 process, run every day by <a href="http://www.jetbrains.com/teamcity/" rel="nofollow noreferrer">TeamCity</a> on a dedicated database.</p>

<p>We've set up several Selenium tests now but It's not as used as planned.</p>

<p>Reasons are that tests are sometimes broken for other reasons than regressions (data may have changed, stored procedure may have been recompiled and so on).</p>

<p>I would like to know if there are big success in user interface testing and if so, reasons to that. Commons errors may also interest me.</p>

I use http-unit which has the added benefit of working before any styling has been added to the page.
http://httpunit.sourceforge.net/
You can attach the tests to run in the integration test phase for maven2.
From the site
Written in Java, HttpUnit emulates the
  relevant portions of browser behavior,
  including form submission, JavaScript,
  basic http authentication, cookies and
  automatic page redirection, and allows
  Java test code to examine returned
  pages either as text, an XML DOM, or
  containers of forms, tables, and
  links.