Funny thing is, I was aware of the feature, but had incorrectly assumed how it works. My assumption was that the feature was only available in-network (to other

Funny thing is, I was aware of the feature, but had incorrectly assumed how it works. My assumption was that the feature was only available in-network (to other Gmail addresses) and actually recalled the message from the server, so long as the recipient hadn't logged in and seen it already. After reading the Gmail blog entry on it, I'd call it an invisible delayed passive confirmation, since Gmail labels it "undo" rather than "cancel." Makes perfect sense, though.