One of Demon's Souls greatest features is its online connectivity. Players will be able to leave hints for each other, "replay death scenes", cooperatively revive dead players, or invade other player's games to "wreak havoc." Hope your friends aren't jerks.
Atlus plans on providing "updates" at E3 later this year, so stay tuned for more. Check out the Japanese trailer after the break.
[Thanks, David B.!]