My testimonial about Hudson
I have tried some tools for Continuous Integration before, like Cruise Control and Continuum. At the time I have tested them, some years ago, the first one was not very simple to configure and the last one used to be visually more interesting, but the project was just starting, so it had some problematic bugs. Because of that and because of the project build that I was working was simple without dependencies (it was just checkout the code from SVN, compile, run the tests, publish the results, deploy the application and notify about breaks sending and email and a SMS), it was decided schedule the Ant scripts directly as cron jobs. It actually worked very nice in that context.
I have been reading a lot of nice things about Hudson, but just now (I am late!) I got the opportunity to really try it. I am now getting in love with it! First of all, it is easy to install (you can run it directly or deploy the war file in a servlet container, like Tomcat or Jetty). It has a very nice and intuitive interface (you can start using it without read big docs). It is easy to administrate (you can install and manage nice plugins, like the Deploy one that publish war files). It is easy to create new jobs (all the tasks that I said before are already there to be set and, for example, you can define a strategy to poll the repository and build only if the code have changed). It has a whole community ready to help you (try to post a message in the users list). Read more about its features here.
I would suggest you to take a try (launch this Java Web Start and go to http://localhost:8080). If you are new to Continuous Integration, do not think tools can solve your problem, otherwise make sure your team is ready for incorporating the practices that will later bring it.
Hope you have a sunny day with Mr. Hudson!