Google's original plan was to have Android phones on the market in the 2nd half of 2008. The WSJ cites several carriers having problems getting Android phones ready for a roll-out still in 2008.
Other problems that could cause more delays are apparently around getting applications done for Android in time. As Android is open, carriers want to get custom applications ready to differentiate themselves.
Some application developers are focusing their resources on the iPhone platform due to the much bigger hype surrounding the new iPhone 3G and imminent launch.
More details on the WSJ.