At the moment most of the merchants are added via CPA networks, so the dev time is fairly minimal. I expect this will change when we exhaust all of the top merchants on the affiliate networks and go looking for more 'premium' merchants.
There's no location detection just yet, but it does work with .com/ca/co.uk, you just have to put the relevant URL in the first place.
Oh, and there's no chance you've solved my personal bugaboo, and can redirect to Amazon.COM/CA/UK depending on a person's origin, is there?