Assuming the "We Know" note seen in the Quakecon footage a while back is a note given to the PC to by a member of the Black Hand to notify them the PC has been observed by the Dark Brotherhood, I'm wondering what choices the player will have to make in order to get that note. The obvious answer is to kill someone but I hope not just once like in Oblivion. I'm hoping it will depend on distance from the DB location. For example, say the DB is located in Solitude. If the PC kills one person in Solitude, there will be a higher chance (not 100% chance, maybe 85%) of receiving that note. But if the PC kills three people in Whiterun, there will be a lower chance of receiving the note. And so on and so forth.
But this is how I imagine what happens after PC receives the note. PC goes to sleep for a little while and then comes a loading screen which triggers the first DB quest when you end up in the DB Sanctuary after being kidnapped by a member of the DB. Kind of cheesy, I know. But that's kind of how I see it.
Discuss everything Dark Brotherhood.