As of September 2, Panel Picker voting is closed. You can, however, still leave comments on the proposals you find interesting. We will announce the first set of accepted panels on Thursday, October 2. Stay tuned to the SXSW Interactive Festival website for these announcements, or e-mail us if you have questions.
Data communication between the clients and the server can always be intercepted. From clear text, to AMF, simple encoding, symmetric encryption, shared keys, and asymmetric encryption, they all can be seen. It is extremely hard to write a bullet-proof solution, but if you really need it, learn it here.