this would imply that SMS are actually sent X time after you press "send"... Most people like their SMS sent instantly

This will be a Feature -- Depends upon user to Turn it On or Off.

Fakhr-E-Alam | SymbianTweet.com

I can see some value in this. Implemented the way Gmail does it (just waiting 5 seconds before the email is really sent) would be nice way to do it.

The delay should be user defined, in seconds. And it should be a free choice not, a series of pre defined ones.

awesome to prevent life loss....specially in India Roads....

I have often the same problem, a mistake when I send the message and then I must hurry into Sending inbox to stop the transmission before it's too late.

Sometimes I remove the battery to stop it.

Even better, add a skipable countdown timer to all delayed messages with the "Send NOW" option. This way if you leave it on for several seconds or minutes, you will know every time that it's been delayed and you can cancel it/send immediately.