Bill Thompson has written a good article
here on Privacy, Trust and the conflicting interests of users and for-profit providers
Trade union activist and online campaigner Eric Lee put it succinctly in a recent blog post when he noted that 'Facebook is a poor replacement for a real online campaigning strategy for unions. And it makes us vulnerable to the whims of those who own the company'.
Hushmail seems to offer a good service, but its 'simple' service offers little real security when it matters. Far better to install your own encryption software, like the freely available GnuPG, and take responsibility for your own security.
And Facebook may make it easy to set up a group, but it will never be as good as having your own server, your own code and your own security mechanisms in place. Organise a group on Facebook and it belongs to them; organise it on your own server and it belongs to you.
Especially when, as we have just found out, you can be
booted off Facebook without notice (we noted the similar risk as well with
sites in trouble)