I realize this is something of a necro-bump (2 years!) but I found this thread extremely useful, particularly the discussion of why a disclaimer doesn't work. For anyone interested, this is what I've put in my picks to explain to others why those disclaimers are invalid:
Why Your IM Disclaimer Is Invalid
IM disclaimers are NOT valid. A disclaimer can only exist where there is a contract between two parties, such as a warranty which may disclaim responsibility for damage incurred due to mis- use (manufacturer and purchaser) or terms of service (user and service provider). I agreed to the ToS when I clicked "I Accept", but that did not involve you; it established a contract between me and LL. You are in no way party to that contract. Your contract, when you agreed to the ToS, is between you and LL. Therefore, you cannot disclaim any part of *my* contract, and I can and will report you for violation of the terms of service. You must have my express consent, meaning you must actively ASK me and I must actively AGREE. Only YES means YES; anything else means NO. Including silence. http://community.secondlife.com/t5/General-Discussion-Forum/IM-Sharing-Disclaimers-are-they-valid-Is-there-any-way-to-make/td-p/995829/page/4