Adama is a Cylon.
Bare in mind that this can relate to both the Commander and Apollo. Now, personally, I don't believe this, for a few reasons.
1) It's stupid to have more than two major Cylon players on the Galactica in the show. We have Sharon and Gaius (who is not a Cylon but is being manipulated by one). If then either Lee or the Commander were Cylons, we'd have only Starbuck, Tigh and Tyrol within our main cast who aren't Cylons. Who then is fighting against whom? It outweighs the odds in a ridiculous fashion, makes little narrative sense, and would lead to an extraordinarily flawed show.
2) They'd have hinted towards that earlier. They've been heavy with the Sharon references, if they wanted to show someone else was a Cylon they'd have done so, in various different ways. It's a narrative device which covers your arse, so that when you pull your giant plot twist, you can round on the disbelievers and say "hey, didn't you see in that episode when he did that thing? that was a signifier!" There haven't been any signifiers. I've been looking.
3) Both the Commander and Lee have full and long histories behind them. Lee is the Commander's son, for instance - you couldn't really get away with him being a Cylon unless the real life person has been replaced with a Cylon version. That would sort of be acceptable, but reason 1 still rings in my ears.
Okay, I just don't like the idea of either of these characters being Cylons. I like them too much for that.
This episode was interesting, for a variety of things, but not quite interesting enough. I found it long and cumbersome at some points. I couldn't help but think it would have been better if there had been an explosion after all. This episode seemed more derivative than the others. Obviously it's further building on what we know, but it just felt like it was rehashing a lot. I liked how Sharon on Caprica seems to be going against her orders, and also how Gaius lied about the Cylon detection, they were quite good twists. However, on the whole, the interrogation scene went on too long, and I was frankly annoyed with Starbuck for letting that Machine get to her. So I think this is my second least favourite installment, but it's still 10 times better than any other show at the moment.
Of course, it doesn't help that once again we saw Apollo all of once. He's a main character God damn it. We want Jamie! I like the show in its own right, but I really like the show with Jamie.