What a great, cool episode of House! It focused entirely on Wilson, showcasting this oncologist at work and shoving House to the background for a change.
Aside from seeing how Wilson interacts with his nurses, we also got to see him save a patient's life by diagnosing that his cancer had gotten worse because he was acting depressed for a day. But the crux of the episode was how Wilson dealt with a former patient that found his way back to the hospital (played by Joshua Malina).
Wilson and this man had become friends after Wilson cured his cancer in 2004. But now he was back and in back trouble, trouble that got even worse after Wilson doubled his chemo in an attempt to cure him again. Turns out, the guy needed a new liver and he needed it quickly. Enter Wilson himself!
Again House's wishes (he admitted that if Wilson died, he'd be alone), but with a blessing from Cuddy, Wilson donated a piece of his liver to his dying friend and saved his life for a second time. When he awake from surgery, House was by his side, as the interactions between these two have become the best part of the show.
To close the episode - and the 2009 season - Wilson made an offer on a loft for him and House to move into. It was actually the same loft that Cuddy had been trying to purchase with Lucas, but Wilson said that he was angry at Cuddy for hurting his friend (House) and dating Lucas. This was the semi-angry side of Wilson and House loved it. So did we.