Re: Disagree with blocking email on personal phones
If you use Google Apps and POP3/IMAP is enabled, then people can sync stuff to their local E-mail client, and it won't honour a remote wipe.
If you don't, then at worst people can screen-scrape the web interface. I remember an old proxy for Yahoo! mail which used to do this, because Yahoo! didn't provide a POP3/IMAP interface at the time.
If people actively want to steal company secrets, they can do so easily: for example they can just POST files to a HTTPS server they control outside. That's not counting the obvious things like carrying home USB sticks and printouts in your briefcase.
Those things are all very difficult to avoid, and you can't avoid trusting your staff to some degree. What you can do however is use these mechanisms to minimise the impact of *accidental* data loss (e.g. stolen laptop); to *monitor* activity and look for suspicious patterns; and to have *accountability* and traceability.