Check out this video of Ben Adida at Google giving an overview of cryptographic voting and read his afterthoughts.

Having given similar talks on Punchscan, I know how tricky it is to explain the concepts to a lay audience, especially the verification technique (the divide between individually verifying the inclusion of your ballot and collectively verifying the decryption and tallying of all ballots–this is in need of a good real-world analogy). He does an excellent job.