Spoiler:George enlists in the army.
Izzie and Alex get married.
In the season finale Izzie goes into cardiac arrest, but she has wrote a DNR form, so they wont help her, until Alex pleads and then they try to save her.
A John Dough arrives in the hospital, they dont know who it is until he writes 007 on Merediths hand and she knows it George, they try to save him as he is in a bad way.
The finale ends with Izzie in the elavator and George meeting her, its unknown who dies and who survives