Enforcing code format in an organization needs discipline. And the best way to do that is by doing some automation. A plugin for Maven will be a easy decision if your organization has used Maven to manage the build.
Compared to Jalopy, which is now not free, I find Eclipse formatter has the flexibility we often needed. Although it is not bug-free, for most cases it is more than enough.
However, I concerned by the fact that official maven doesn’t have the latest jar of Eclipse JDT. It still only has version 3.3 of it. Hopefully they will have it soon, especially after Helios is released, which bring a lot of improvement to the Java formatter.