@thet. phonehome is not really my idea. Others have already tried it.
What I'm saying is that, while a great idea, we can be pragmatic and get the same data more quickly by asking admins worldwide to install a python script similar to
data = context.portal_quickinstaller.listInstalledProducts()
return """<form method="POST" action="http://plone.org/census/@@rapido/plonecensus/block/submit/add">
<textarea name="data">%s</textarea><input type="submit">
</form>""" % data
On the plone.org side we can ask further questions about business sector etc.
Later we can improve it with some core phonehome feature that knows when plugins have changed.