I asked the Piwik Developers if they could support WooCommerce to:
A Member answered:
We would like to support WooCommerce of course, just like all other open source ecommerce application! supported are: http://piwik.org/integrate/
Do you know someone who could build a good quality plugin for piwik with an ecommerce support?
We could help a little bit by sending a 150 eur bounty for example, and definitely help with feedback and showing to the community.
Will the WooCommerce-Team get in touch with the Piwik guys? I really would appreciate that.