One of our team members sent me a link indicating that Zfone could be used to secure Google voice and video chats with ZRTP (as shown in the screenshot above). I did some research, and it turns out that one of the Zfone developers managed to get this wired up a few months ago, as documented in an entry on the Zfone blog. For those not familiar with Zfone, Zfone is a small download that encrypts voice and video traffic so that it cannot be intercepted or tampered with, all with minimal setup. You can read more about Zfone/ZRTP on the Zfone FAQ.
I haven't had a chance to try this out yet, but it's pretty neat that the Zfone team was able to get this working without any support from us (yay standards!). If you want to give it a shot, you can download the Zfone Beta for Windows, Mac, and Linux from this site.