Gmail used to do that with their attachment. You choose the attachment, and it silently starts to upload. Most applications wait for you to hit "Send" to start uploading.
Thank you, Mitch Hedberg. Also, and strangely appropriate for an Instagram thread:
One time, this guy handed me a picture of him, he said,"Here's a picture of me when I was younger." Every picture is of you when you were younger. "Here's a picture of me when I'm older." "You son-of-a-bitch! How'd you pull that off? Lemme see that camera... what's it look like?“
