We all knew that was coming. The Demacrats are pissed at Bush. They knew that a Dem was more than likely going to be voted in for President, and the new president would get to choose the position. Therefore, the democratic house and senate failed to act on Bush's appointment, so that when Obama gets there, he nominates and then the FCC is democrat controlled instead of republican controlled.
That is why back a few months ago, they offered for Kevin Martin to step down in exchange for Tates approval. He did not take the offer, Tate technically got the shaft.
Although Tate was renominated by Bush last year -- her term expired in June of 2008. It was not renewed by Congress, but by Law she was able to stay in office until this month -- which is when Obama can replace her... which he will.
Which leads me to the second point -- which is the party in power ALWAYS has the ability to appoint one extra person from their party to the FCC.
So Tate's stepping down is just the way it is -- because she was not going to have her position reconfirmed by Congress anyhow... with the changing of Party in the White House. As soon as Obama became President elect - because of timing, her position was pretty much eliminated... there was nothing she could do.