Encrypting SMS and calls Is it possible to encrypt calls and SMS messages between two Android phones (or even from android to iPhone)?

This firm delivered a beta on Android Market before: http://www.whispersys.com/
What you want is Zfone on Android. It is currently not native available, but there is a bug report on the offical Android tracker asking for it. Star it, but don't leave a comment without content. This is the best chance to raise Googles attentions on this.

Whats currently possible on Android is good described by the guardian project in this blog post. BTW: The Guardian Project is good resource when it comes to to privacy and security on Android.