There is no "liberal media" and there probably never was. Despite what righties would love to believe, the media monopolies of today do not favor the left.
Mostly, it is all about selling out to their corporate bosses and being lazy. Nothing more, nothing less. How else to explain wasting time on stories about J-Lo or "Ocean's Twelve" ?
Now we are getting all these stories about the incompetence of the Bush administration. Now the media dares to cover stories about how Bush and his henchman have lied to our soldiers, ill-equipped them, and in general not supported our troops.
The reason they suddenly feel free to criticize is not due to any left-wing bias; it's because the election is over so big media's agenda is safely in Republican hands and also it's easy --- a soldier put himself on the line (and yeah, he talked to a reporter beforehand) and handed the media a big story.
Yahoo! News - Charges of Poor Planning in Iraq Revived