CBS and CNN hire independent polling companies to conduct their polls.  Generally the bigger news institutions are not regarded as injecting bias into their polling but you never know about the accuracy of the poll until you see what's known as the "crosstabs" - what percentage of the poll was made up of self-identified democrats, republicans and independents.  

Right now party identification favors democrats in this country, so the polls I referenced will have definitely sampled more democrats than republicans. However, the CBS poll sampled UNDECIDED voters so it's hard for me to see how they were in the tank for Obama.

I would point out that just a few weeks ago CBS ran a poll after the GOP convention that had Obama and McCain tied with a headline blaring that McCain had made up 8 points on Obama.  

CNN has similarly had plenty of polls that favored McCain when he was polling well or that showed Obama slipping.

As far as Time Magazine goes, the grading was done by Mark Halperin so you can judge for yourself whether you think he's in the tank for anyone.

Online polling from ANY source including Drudge or more progressive websites are not considered to have the kind of methodology that leads to accurate results and no one serious references online polling as dispositive.