AI

It probably is going to have a major impact on the story. Theories abound:

Alec and Ellen Ryder did this on the sly before the Initiative was even founded. Possible, because I imagine it could be something done in secret that doesn't take a lot of room to do. I could be wrong.

Alec found tech somewhere in his wanderings to give him and Ellen a jump on the development.

The Alliance gave sanction to the couple to develop it.

And many other theories, I'm sure.

Either way, SAM's development is going to have enough of an impact that it supposedly has its own story and explanation in game. I look forward to hear it.

It wasn't in Mass Effect 3 even though Shepard's implants were far more involved then SAMs seems to be, plus the constant threats of hacking, indoctrination, and Miranda even mentioned the possibility of a 'control chip'. 

It reminds me of Javik's conversation about the Zha'til.

Ryder (and a handfull of people on the Pathfinder team) is everyone now?

I was using "everyone" as a generality, not that I actually meant everyone in the entire game. But still those few, and the people around them, still have no objections that an AI is being implanted into their brains? Yeah so believable

i actually just double checked because i wasn't sure but SAM is not implanted in anyone's heads.

There is a neural implant that is connected to Sam. This implant is within the path finder's brain Sam sees and feels as ryder does. It has direct access to the user's brain offering advice to situations, technical enhancements, etc... So technically it is within their brains. It's an AI, what's stopping it from causing harm? It's funny though we have the quarians, the main race who dealt with AI, not trust AI. We have cerberus, an organization who uses everything at their disposal, but still don't trust AI. We also have the council and basically the entire galaxy that don't trust AI. But Alec ryder, a vet from the first contact war, knows everything about AI that he trust to invent one and put a neural implant in his children that gives this thing access to their sensory nervous system. it's crazy to me.

When he finally finds out the secret, he realizes that the Ai departed and he's on board. 

that's communication. Ryder is in full control of the system just Sam recieves information and makes a suggestion to Ryder and then tells the implants what to do in the event Ryder takes him up on the offer. Communication.

"Tactical enhancements" isn't just the receiving of information. Sam is involved in Ryder's sensory processes. 

You know the more I think about it the more I think these odditities are 'intentional'. Its sort of a weird way of building hype, and I think it goes back to something I heard about the ME 3 endings...not sure if its legitimate of course, but the claim was advanced that Mac Walters basically came in and said 'speculation for all' or something to that effect. Which is a terrible way to end a game, but an interesting way to Market one. Because there are issues. There are a few issues in the lore where the Marketing seems to be pointing towards an answer but not really providing one. This is one such example. Because Sam does not seem to quite fit the lore, but yet, the information provided seems to point towards an answer. So...we are discussing it, specualating on it, and thus thinking about the game.