It's called kishke in Yiddish, and if prepared according to kashrut laws (i.e. no blood/pork, and the animal is correctly slaughtered, etc), it's kosher.
Read what I said again...I said it was doubtful you could find blood sausage on a kosher website which you find is not wrong.
Kishke is made of beef intestine and ground meal (by accounts of wikipedia, I am no expert on Jewish cuisine) which is not the kiszka I presumed people on this Polish forum were referring to ie. Kaszanka.