That's my theory, speaking as someone who correctly pegged that Harry Potter was a horcrux (please, if you haven't read Deathly Hallows by now, you don't DESERVE a surprise ending).
Think about it -- River and the TARDIS do seem to get along really well. The TARDIS can cross connect events in the past, present, and future. The man she loves. She knows the Doctor's real name. The Doctor is clearly hot for Riversong during their first kiss, and he calls the TARDIS "sexy". The TARDIS complained about the Doctor pushing the door in instead of pulling out, but didn't mention the noise made because he leaves the brakes on. I remember this from School Reunion:
Sarah Jane Smith: Does he still stroke bits of the TARDIS?
Rose Tyler: Yeah, and I’m just, like, “do you two want to be alone?”
This might also explain why she isn't as thrilled with the 11th Doctor. They didn't call him David Ten Inch for nothing! (Note: I have no proof, I just couldn't let a cheap gag get away.)
Am I the only one wondering if Joanna Lumley might become the next Doctor?
That said, this episode was soooooo Neil Gaiman, just like you could tell what episodes were written by Douglas Adams. The TARDIS demanding, "Where's my thief?!?" "I have corridors." Gaiman's fingerprints were all over this episode. Best bit, though, is when the Doctor says, "I don't know what to do," then says, "That's a new feeling," then starts smiling and enjoying it before slapping himself.
Speaking of Douglas Adams, I guess we can put that still from Shada to rest as a production mistake. The TARDIS specifically identifies herself as a Type 40, not a Type 39.
That said, Davros is looking more prophetic than ever. The Doctor turns people into weapons to do the dirty work he won't do. And here, he turned the personification of his TARDIS into a weapon to save the day.
I think I deserve a little credit for the exchange where the TARDIS tells the Doctor, in response to his complaint that she never takes him where he wants to go, that she always takes him where he needs to go. Years ago, I had told people that the reason for the TARDIS wandering around the universe was the telepathic link to the Doctor. He wanders, it wanders. When he needs to go to a specific time and place, it does. I figured it was just the link and a question of focus. Maybe? Kinda sorta?