Ptracekm is a kernel module for Linux 2.2 (Possibly 2.4, but untested) that blocks the ptrace() syscall for all users except root. This should effectively prevent local root from being gained via the latest series of ptrace() exploits.
18768578edd24d9a17c34381bd0f0c288641287232e6fd41e7207a05887a2bae