This 22 page in-depth report evaluates two popular mobile security solutions:

http://blogs.pcmag.com/securitywatch/2011/06/symantec_paper_explores_mobile.php

A Window Into Mobile Device Security
(Examining the security approaches employed in Apple’s iOS and Google’s Android)
http://www.symantec.com/content/en/us/about/media/pdfs/symc_mobile_device_security_june2011.pdf

QUOTE: The mass-adoption of both consumer and managed mobile devices in the enterprise has increased employee productivity but has also exposed the enterprise to new security risks. The latest mobile platforms were designed with security in mind—both teams of engineers attempted to build security features directly into the operating system to limit attacks from the outset.

However, as the paper discusses, while these security provisions raise the bar, they may be insufficient to protect the enterprise assets that regularly find their way onto devices. Finally, complicating the security picture is the fact that virtually all of today’s mobile devices operate in an ecosystem, much of it not controlled by the enterprise—they connect and synchronize out-of-the-box with third-party cloud services and computers whose security posture is potentially unknown and outside of the enterprise’s control.