User acceptance?
As a website sysadmin, this sounds like a fantastic idea. Being able to offload my SPAM monitoring to a third party sounds like a real time saver.
The only catch I can see is in the service agreement. The Mollom services requires a website visitor's "name or nickname, IP address, membership ID, OpenID, website URL and e-mail address" to be passed on. As Mollom is a third party, I would need to seek permission from all my members, or at least those that post content, before introducing Mollom. I would expect there to be some objection to this.
What have others found? Are users prepared to pass on this information in return for a SPAM-free website?
PS: The SPAM filter decided this post "could be spam" :)
Privay
I think this depends on what you already have for a policy. For example, the policy on a site I operate has something that says, "XXXX discloses potentially personally-identifying and personally-identifying information only to those of its employees, contractors, and affiliated organizations that (i) need to know that information in order to process it on XXXX’s behalf or to provide services available at XXXX’s websites, and (ii) that have agreed not to disclose it to others. Some of those employees, contractors and affiliated organizations may be located outside of your home country; by using XXXX’s websites, you consent to the transfer of such information to them. XXXX will not rent or sell potentially personally-identifying and personally-identifying information to anyone."
The Mollom agreement says they aren't going to share the info. What I put above is from wordpress.com/automattic (they released their privacy policy via creative commons).
Wouldn't that be enough?
Probably
Such a policy might be enough. However we don't really have one at all for our site. So we'd be asking after the fact. So we might get a bit of resistance.
And we're also bound by privacy laws in our country (Australia), which require proper consent for this sort of thing.