Gareth is signing in the Holzheimer booth (think I spelled that right; it's on his site). Dunno about Barrowman... it might depend whether his appearance is sort of sponsored by somebody (like Gareth and the Holzheimer people) or whether BBC is sending him or what. With the two of them both going though I'll bet they'll add a Torchwood panel to the programming track, if they haven't already. You should email the Comic Con people and ask. Also, I'm totally depressed I'm going to miss it. :(