We've been using the 2.2-beta-2 plugin for recent Apache Portals releases (not 2.2-beta-3 because of MASSEMBLY-405) en encountered a few annoying issues.

1) Used together with "apache-release" profile of the Apache 6 pom, the maven-remote-resource-plugin is also executed by default (as it should) but that produces a velocity.log file in the project root which is then included by the "project" assembly. The main problem IMO is that predefined assemblies do not take any configuration overrides/extensions.
As each (ASF) project is different, the likelihood some temporary build output is produced during the release and subsequently "assembled" should be expected, the velocity.log produced by the m-r-r-p just being an example.
My preference therefore would be that predefined assemblies do accept additional configuration settings so we can include/exclude specific files as needed.
If that is not doable (on short notice), the "project" assembly as a minimum should add an exclude for velocity.log as disabling creating that file on the m-r-r-p doesn't seem doable either.
NB: see also http://issues.apache.org/jira/browse/PORTALS-16 as reference.

2) Related to the above is the fact that the "project" assembly uses classifier "project". This is by design of course, but as we are used to providing source distributions with a -src postfix, and end-users will look for that by default,
it would be good if the classifier can be overridden/configurable (using the predefined "src" assembly instead clearly isn't possible for this purpose).
However, even while the "classifier" is (still) specified as a deprecated optional parameter, it is completely ignored (now?).
I strongly suggest to re-enable the "classifier" parameter again, or provide a new alternative parameter for this purpose.