Here is a good news for Nuxeo 5 : Sun CEO
sets open source Java time frame

As we read in a few discussion threads after the release of NXRuntime and Nuxeo Core, some
people were pointing out that, with our Java switch, we
weren't using a full open source stack anymore. These discussions will be
over soon.

As well, some people asked us if we considered making Nuxeo 5 running using
gcj. Well, ... we have been trying to leverage gcj with the NXLucene
project where we were using Lucene
through gcj. This is working ok but what a pain... It appeared to be
extremely complicated to find the right version of gcj depending on the
target platform on production and that caused us lots of worries... So
definitely not a viable option. Ask the hosting companies if you are not
convinced ... As well, a lot of work is required at application level while
trying to port gcj-based application on upper versions of gcj because of
bugs in the compiler itself. So much frustration...

Furthermore, we can expect Java enabled Linux distributions out of the box
in the future with Java applications pre-installed and shipped with the
distribution itself : for instance JBoss

Because of the fact that Nuxeo bas been caring about open source for more
than 6 years, playing the open source game and choosing a core business
fully based on a transparent open source model, we are more than happy that
this time frame set announcement comes up almost at the same time as the
release of Nuxeo 5.

(Post originally written by Julien Anguenot on the old Nuxeo blogs.)