Ben Reyes is 22 year old British “entrepreneur, developer and hacker” who discovered how to access the complete email history of the previous owner of a domain. With this information he also accessed the person’s Amazon account and has access to all sorts of aspects of the former owner’s identity. It seems that Google gives you access to the former owner’s Google Apps GMail account if you can prove you are the current owner. You now have access to all of their old emails.
Read his post Don’t Let Your Domains Expire with Google Apps for all of the details. Most domain developers won’t be using Google Apps on domains that they will allow to expire. This is an issue primarily if you change brands for your business. Don’t ever abandon a Google Apps account.