you know who's connected where?
Great question. If you have Torbutton installed, the Decentralized SSL Observatory will use Tor to submit the certs via an anonymized HTTPS POST, and warnings (if there are any) are sent back through the Tor network in response.
If you don't have Torbutton, you can still turn on the SSL Observatory, in which case the submission is direct. The server does not keep logs of which IPs certs are submitted from, though this is of course less secure than using Tor.
Before you can turn the Observatory on, we have a UI that tries to explain all of this elegantly and succinctly, in language that even not-super-technical users can understand.
The original design document is here: https://trac.torproject.org/projects/tor/wiki/doc/HTTPSEverywhere/SSLObservatorySubmission