A new role and authentification system is now available with PIWI 0.0.6. You can now add your security mechanisms in the site.xml. Additionally you are able to create your own RoleProvider and get your reles whereever you want.
A Word- and a Excel-Serializer has been added. Those are very simple but will do their job.
Meanwhile the configuration of a PIWI site is to complex to keep it within the site.xml. It has been extracted to config.xml. Ant-file will simplify the build and Unit tests make everything more stable now (hopefully 
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