As pointed out by Mac Rumors supplies of MacBook Pro models are beginning to become tightened ahead of a rumoured refresh. According to the rumour site "one major retail chain has reportedly notified its branches that it has been unable to fulfill replenishment orders".
Although online Apple stores around the world continue to quote 24 hour shipping times, some models on Amazon are showing shipping estimates of "1-2 months".
Reduction of stock in the supply chain is a good indicator that Apple is reducing the number of items in the channel ahead of filling it with new models.
The MacBook Pro was last updated in April 2010.