Remember due to the writers strike Heroes was smart and filmed two endings to the season. 1 to tie up loose ends if they did strike and 1 if the strike finished in time.

[spoiler=wer]We are not 100% sure that it is Claire's blood as we don't know if her blood has the healing ability yet, but she may...also it might seem like someone messed with the Milk Man (i.e. Adam Monroe) for Claire to have healing abilities.[/spoiler]