The reason for the switch is that AL 2.0 is more permissive than LGPL 2.1 and can be integrated with other projects / products more easily. Also, AL 2.0 is one of the most frequently used licenses in the open source world , and you can't go wrong with that, can you ? :-)
I've received quite a number of requests to change the license over the years, from the open source community and from companies trying to integrate JGroups into their products.
This change should increase acceptance of JGroups with other open source projects or commercial products.
So what would the impact of this change be ?
- For projects / products using a current (<= 3.3) JGroups release, nothing would change (they're still licensed under LGPL 2.1)
- For projects / products upgrading to the AL licensed release (once it's out), nothing would change; the AL 2.0 license is even more permissive
Note that Infinispan is looking into making the same change, see  for details. As Infinispan consumes JGroups, it is important for JGroups to have the same license as Infinispan, or else integration would be a nightmare; it's hard (if not impossible) for an AL project to consume an LGPL project.
Changing the license would be done in the next JGroups release. Whether this will be 3.4 or whether a license change warrants going directly to a 4.0 is still undecided.
We're currently working with Red Hat's legal department and the community to see whether this switch is possible and what needs to be done to make it happen.
Opinions ? Questions ? Feedback ? Please post to this blog, or the JGroups mailing list.