So, like others in this topic, I have to wonder... How are religion and ideological choices going to affect diplomacy as it is right now? Flawed as its execution may be, the idea behind the current diplomacy, if I remember correctly, is that the AIs are supposed to stand for real players, who are actually trying to win the game. Players who shouldn't be swayed by something as arbitrary as which religion you have (so that you won't have a case where Isabella of Civ IV is the dominating superpower who could wipe you out really easily, but doesn't because she's really happy that you share the same religion).
Now, I didn't mind that so much in Civ IV because that's the way the AI were for a lot of things; you could share the same civics and religions, give them stuff to make them happy, and they were programmed to not declare war on you if they were pleased or friendly (depending on the character). But the AI design of Civ V is fundamentally different; the AI isn't meant to be swayed by things like that (isn't that why they got rid of Civ IV's religion system? Because it didn't mesh with the new game well? I could be wrong...). I can't really imagine this system being halfway between the two AI designs, since they seem so different.
I do like to imagine other ways in which religion and ideology can affect diplomacy. More trading options perhaps? Maybe you can only make a declaration of friendship with leaders of the same religion (or research agreements are more effective, etc.)? I have a hard time coming up with ideas of how religion could influence diplomacy under the current system.
That being said, other than questions about diplomacy, I'm really interested in the way the religion system system is designed. It sounds really cool, and quite a bit more interesting than the way Civ IV implemented it. (Here's hoping they balance it properly...)
One thing I really want: Make declarations of friendship worthwhile, either by removing the AI's "friendly requests" of 30 gpt or by allowing us to make such a request as well (and keep the AI's request reasonable, I was once asked to give all of my 1800 gold). I like the idea behind the declarations of friendship acting as temporary guarantees of no war and of favorable trade agreements for both sides, but right now the AI's demands can be more costly than a war against it...