Glad that we have the white hats keeping things safe. It's amazing the crazy things you have to do to securely pass data between sites.
postMessage is okay, and is much preferable to wormhole iframes, nix or other ways of doing cross-domain. You still have the problems of doing origin verification (which can be done, with care).
Flash is still needed for older browsers (hopefully not for long now that IE6 and FF3.x are rapidly declining)
Unfortunately, so many people still depend on IE7, so we are still stuck depending on Flash as developers for a while more.
What's wrong with postMessage? I'll never understand why anyone uses Flash in this day and age.
Adrian Colley, Dec 17 2011 on 1500wordmtu.com