If PBS needs all this money from the federal government every year, this raises two huge questions:
#1 - Where is all the Tickle-Me-Elmo money going?
#2 - Can we pledge-drive through this?
In all seriosuness though, I invite anybody who claims that PBS is only sponsored by the federal dime and 'Private Foundations' to actually watch some PBS. Charlie Rose and PBS News for example start with a mix of adds from both major corporations and Foundations (many of which are pretty much just partisan political think tanks anyways - where do you think the foundation money comes from?).
Pfizer sponsoring the Charlie Rose Brain Series has got to be the most hilarious by a mile.
After googling to try to find a few more examples of the major corporation commercials I've seen on PBS, I did come across this interesting PBS page on underwriting. Apparently you can buy a 15 second commercial before most major shows on PBS that will only air on a certain affiliate. Who knew?
http://www.wqed.org/about/underwriting_tv.php