FYI, if you're using Twilio: https://twitter.com/twilio/status/522446663130963969
"If you are encountering trouble with inbound Twilio requests while mitigating the SSLv3 vuln, contact help@twilio.com for direct help."
(That is, they have to manually enable TLS on your account.)
Also, if you're using GET requests with ExactTarget, you'll run into the same thing, but I haven't heard back from them if / when they'll have that fixed.