Now that I have your attention: Download the RedPhone / Text Secure Apps Right Now:
RedPhone is a highly secure end-to-end VoIP app (like Skype, but actually secure) that automates encrypted voice communication. Once installed by both parties, the RedPhone app will prompt the caller to encrypt if desired. Text Secure encrypts text messages (including multimedia messages). Take 45 seconds to install the apps and SHARE WITH ALL OF YOUR FRIENDS.
Military grade encryption automatic if receiver has RedPhone installed!
Matthew Green of John Hopkins says:
RedPhone/TextSecure
RedPhone and TextSecure are developed by Moxie Marlinspike's Open Whisper Systems.
RedPhone does a much of what SilentCircle does, though without the paid subscription and termination to POTS. In fact, I'm not quite sure if you can terminate it to POTS (I'll update if I find out.)
Like Silent Circle, RedPhone uses ZRTP to establish keys, then encrypts voice data using AES. Consequently, most of what I said for SilentCircle also applies here, including the use of a short authentication string to prevent MITM attacks.
Overall code quality: After reading Moxie's RedPhone code the first time, I literally discovered a line of drool running down my face. It's really nice.
In fact, it was so nice that I decided to rough it up a little. I assigned it to the grad students in my Practical Crypto course -- assuming that they'd find something, anything to take the shine off of it. Unfortunately they basically failed on this score (though see 'Other thoughts' below). In short: it's very well written.
