Well if it's good enough for House to go around talking to dead people it's good enough for Cuddy (and Wilson, although at least his dead people don't talk back generally :)

The ending is lovely, with Cuddy being careful not to touch House (afraid to shatter the illusion that he is real?) but being soothed by his presence. I forgot before that this was season five, so she's never experienced him in her bed like this, although at this stage of the show she was interested in the idea - this is maybe how she would have liked him to be, rather than the reality that she would have ended up with if House hadn't died.