A great article was recently posted on the Sonatype blog on the top 10 reasons to move to Maven 3
It will be interesting to see if there is a significant speed increase, as it will be nice to reduce the time of our main nightly build which usually takes about 90-95 minutes.
Luckily, Hudson / Jenkins makes it easy to test out running builds using different versions of Maven, so there is no reason not to test it out. Remember that the reporting has changed significantly in Maven 3, so while your project may build successfully in Maven 3 without any changes to the pom, you will need to make changes to get the reporting working. This article on the Maven Site Plugin explains the changes and shows an example of the new configuration.