The bottom line is, we just don't know enough about the human immune system and all the interconnected issues that lead to allergies, and so pediatricians, who have to treat thousands of children, and the AAP, which has to look at recommendations for an entire country of children, none of whom they know personally, have to take very cautious steps that have broad policy repercussions. You, however, are one mom, with one - or a few - kid(s) whom you know very well. That's why there's so much conflicting info out there. Because we just don't know, but someone has to sound definitive.
That said, for my kids I took the position that waiting until after a year sounded wise b/c there are certainly digestive developmental issues that are resolving/resolved for most kids between 1 and 2 years, and since my kids have had no allergy issues and no digestive issues, I felt comfortable moving forward with nuts at a year. That said, I'm still waiting on shellfish for the twins (my little guys are a year and a half, my oldest is 3) b/c there are shellfish allergies in my family; my oldest had shrimp for the first time around 2. So, you just kind of have to feel things out based on what you know about the policies and what you know about your kids and family history.
The only other thing to consider is something that another mom hit on, which is the allergic reaction itself. Basically, from a policy position, it's better to encourage people to wait on hitting their kids with possible allergens b/c anaphylaxis (the reaction itself, and w/ peanuts and shellfish it's usually respiratory) is easier to handle, medically, in older children. when an infant crashes, you catch it later, it's harder to handle, and much more lethal than if, say, a 6-year-old crashes. So, from a public policy (and litigation-defense) position, you want people waiting as long as possible. But again, these are your kids, not public policy. So, if you feel comfortable that it's unlikely there will be a reaction, and if you make sure that you keep a close eye on your kid for an hour or so after introducing the food the first few times, and you've waited past a year, and there are no other issues... then you're a mom and you're making an educated choice for your kid. and that's what we do. :)