Seems like the pwn2own this time around is going to be putting up prizes of about $100,000+ for people who can find 0-days for a variety of platforms. Especially, the fact that about $60,000 are being devoted for 0-days on the mobile security platform including the android platform etc., indicates a new era of security bugs.
The iPhone (non-jailbroken ones) as well as the BlackBerry application do tend to use signed executables. One only hopes that like the trust-relationships of the SSL-based certificates, the trust is really kept by analyzing the blackberry and iPhone apps.
Tyler Shields from Veracode presented his work of TXSBBSpy (source code URL: http://www.veracode.com/images/txsBBSpy.java; Presentation slides: http://www.veracode.com/images/TylerShields-MonkeyBerries-ShmooCon-2010.pdf).  In this he suggested that when controlled APIs are used the code needs to be signed by RIM but to do that RIM only gets the hash and not the source code.  This presents an interesting situation where RIM could actually be signing something that they don’t really know what it seems to be doing.