"We’ll roll out iPhones when monkeys fly out of my butt"

"The largest enemy of change and leadership isn't a "no". It's a "not yet". "Not yet" is the safest, easiest way to forestall change. "Not yet" gives the status quo a chance to regroup and put off the inevitable for just a little while longer. Change almost never fails because it's too early. It almost always fails because it's too late.”
This is my favorite quote from Seth Godin's book "Tribes - We need you to lead us”, which is a great read by the way.

I came across this hilarious quote by Thomas Wailgum at CIO.com via Dennis Howlett's blog on the same theme:
'When a CIO says, “We think iPhones for our workforce—even though they are more expensive than the smartphone we have standardized on—might be something for us in the future,” he’s really thinking, “We’ll roll out iPhones when monkeys fly out of my butt.”
The point here is that good leadership is not demonstrated by the actions you say you will take, but by the actions you actually take.

Just do it!