Did anyone watch Doctor Who Confidential? I thought I saw the guy who played Mickey (Rose's boyfriend) at the read through, was it actually him?
Probably - as
Jaffa mentioned, he was featured in the publicity shots.
As for the episode itself, WOW. A true cliffhanger, as I honestly don't know how they plan on resolving it. If
the Doctor actually regenerates, then this was an amazingly well kept secret and I wonder who will replace him. If
he doesn't really regenerate though, then I'm curious how they will explain things. Will it not be a
proper regeneration then, either due to them being in a pocket of time (shouldn't matter though, should it?) or if he chooses the same body perhaps? We know that's possible as Romana did this, but the Doctor never has... perhaps it's a male/female Timelord thing.
Hmm, this could actually be the case now that I think of it, as the Doctor's daughter did not regenerate into a new body - perhaps that's foreshadowing of what's to come? 
Regardless, any of the above would then kind of worry me, if there is essentially a regeneration cop-out, as that would be unprecedented and in my mind be the biggest anti-climax for the show.
Maybe he'll regenerate into the Valeyard. Yeah, I've said that so many times and it never gets old...
I'm also very curious to see what happens with Donna. There definitely seems to be more to her, what with the whole "something on her back", that big ring she has and the loud heartbeat on the stairs. Maybe she's
a Timelord in human form like the Master and her big ring is like the Doctor and Master's watches!
I'm also interested to find out what that key is all about that Martha has - perhaps that's the key (pun intended) to resolving everything...
In general, I'm thinking that RTD is going to repeat last year's finale in that there has to be a big reversal of events - perhaps that's how they'll explain things... kinda hope not though... <shrug>
Anywho, great episode and man, what a cliffhanger. I can't wait to see how they resolve everything between Ianto/Gwen, Sarah Jane, and of course now the events in the TARDIS at the end.