First there was:
Sent from my Blackberry
The purpose was to let people know that they should forgive the brevity and the typos, and that the author had a fashionable device. It was soon to be beaten:
Sent from my iPhone
To avoid being seen as trying to be fashionable, a more neutral signature was invented:
Sent from my mobile device
Financial analysts and product managers could advertise their iPhones, but the real nerds had a device that was not even available yet in stores:
Sent from my G1
Even realer nerds needed to point out that Android is not limited to any device:
Sent from my Android capable device
But that seemed a bit too long:
Sent from my droid
In order to make sure readers knew why messages were so long and perfect, quite a few people invented:
Sent from my computer
Really old nerds with beards sign:
Sent from my iBM
Salu2