The format changed between the 3.0 and the 3.1 branches of the GPD, not of jPDL. The 3.1 branch has been out for quite a while. I found several outdated GPD files while looking for an example to deploy and decided to accept the conversion to the "new" format. The GPD files do not even take part in the automated tests - they just contain layout metadata for the designer (and the process image page in the console). Nothing new here, just something that should probably have been done when the new format was introduced.
Are you saying that SOA customers won't be able to use their existing GPD files with 3.2.5.SP2 nor jbpm-3.2.6.GA?
This is a non-issue. The change is purely internal (i.e. it only affects the gpd.xml file) and is completely backwards compatible as the editor does the check and performs the necessary changes after asking the user. This was included in GPD 3.1.0 beta1 and fixed with https://jira.jboss.org/jira/browse/GPD-64 on June 14th 2007, almost 2 years ago.
As Alex points out, the changes he did comprise a number of example process definitions that slipped through the cracks and apparently were not yet converted.