Hypothetically supposing that jquery.com had a lovely little green lock, that wouldn't matter, because on jquery.it a) you wouldn't be looking for the lovely green lock and b) if you did look for it, look here, a lovely little green lock and c) you didn't click the lovely green lock to see who it was issued to but if you did d) it was issued to jquery.it, which matches the address in your bar.

SSL solves one problem, really really nicely: it makes it impossible to eavesdrop between the user and a trusted endpoint. It does basically nothing to make sure that the trusted endpoint is the one the user thinks they are interacting with.