This one's old, but seeing as NOTHING has been posted here, I might as well make sure you're all informed. This one's dangerous.
Anyways, some guy from chroot.org modified a race condition exploit for the linux kernel to work on SMP kernels. This one works on 2.4 --> 2.4.29-pre3, 2.6 --> 2.6.10
http://www.x0r.ca/uselib24.c
Ahh, I remember d.c, I've been looking for this :p
Yep.. patched already.