Ok if you haven't seen Everything Changes yet sorry. We just couldn't wait for you stragglers any longer to discuss some of the potential implications of Jack's big secret. It ties in with an interesting new item in Captain Jack's scrapbook available to all on the official Torchwood Intranet site.
The above newspaper clipping from 1971 (apparently published just a few months before I was born) has an interesting surprise in it if you look at the picture. Chopped off on the left of the frame is a certain Captain looking exactly the same as he does today, it matches that early publicity photo from the BBC.
It would seem to appear that not only can't Jack die, but he can't age as well, and he has been involved with Torchwood for decades and waiting for "the right Doctor" to help him out. My thought is that with him being a former Time Agent himself, he knew he couldn't bother any of the former Doctors with something from their future during the UNIT days, or even pop up and say hello to himself and the old gang during the events of Boom Town, doing so would cause a time paradox. As to why he didn't report over to the London branch during The Battle of Canary Wharf last summer, well I imagine he must have had a hot date.
Now there is of course the other possibility that he simply popped through time somehow to 1971 and zipped back. Afterall you figure Jack would have changed his clothes in 35 years time, but that doesn't make for nearly as interesting speculation. So do you think you know the answer to our question about Captain Jack's whereabouts between Parting of the Ways and Everything Changes? If so please don't be shy, speculate away in the comments.