Waste of time
If you are already agile and have been doing continuous integration without Cruisecontrol then I would like to save you some time.
CruiseControl standard was a real pig to use and possibly the most complex wrapper you can imagine for an ant script. Given that the word "enterprise" usually translates in IT to "pointlessly complex" I do not really hold out much hope that they have significantly simplified things in the Enterprise Version.
What does it offer the agile developer?
* It runs unit tests after a commit to version control - If you are really agile you run the unit tests before you commit to version control. Not, after the rest of the team has already checked out your bugs! And if you have hundreds or thousands of unit tests then you will probably find at least some of them break as you get them running in a slightly different environment (eg, outside of your IDE) for integration with CC - this can take a while to get working and by the end of it you wonder if all the hassle was worth it.
* It runs integration tests - This can be somewhat useful if your integration tests are very slow, but of course you still need to write them and there are other much simpler ways to runs integration tests than spending a day trying to get everything running under cruise control.
* Front end tests - If you are doing a web project you can theoretically integrate selenium tests in, but doing this in CC is a hassle and the testing is usually quite fragile. Once again, if you are bothering to maintain good front end tests, then run them before you commit that way when they break you can fix them as part of your changes, rather than run back after breaking the build for everyone else.
* It does a build. - If your project is too massive to build and test fully before committing then maybe CC could be of value, but really I don't personally know any agile developers who would commit code that didn't even compile, particularly with modern IDEs like eclipse show a big red error mark against the project folder and keep code compiled all the time.
I can see a place for an automated build system in very large distributed projects or to try and move non-agile teams in a more agile direction (this is where CC is usually set up - not in teams that are already agile) but I really hope for these enterprises something a bit simpler exists and that the experience of setting up CruiseControl doesn't put them off the whole idea of Agile development!