The TF2 Official Blog states:
"Any experienced sniper will tell you how irritating it is when your targets keep moving around. The question is how to stop these cheaters from wind-sprinting around like they own the place. And the answer is to pin them to a wall. How? With arrows!"
Update
The URL has been updated to:
http://www.teamfortress.com/sniperupdate/day01_english.htm
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