Most cell phones that send email append a little line to the end that says something like, "Sent from my Blackberry," or "Sent from my iPhone."  Personally I hate this little "feature" and wish people would stop telling me where their emails are coming from.  (Although I'll admit it's sometimes useful to know whether a person is at their desk or not.) 

But just a few minutes ago, I saw a good one in response to an iPhone email:  "Sent from my Desktop Computer.  While sitting in a chair.  In a cubicle.  At work." #technology