Seems Linux is vulnerable to a vmsplice exploit allowing local users to be come root. This affects kernels 2.6.17 till 2.6.24.1. For those building their own kernels, patches for 2.6.22, 2.6.23 and 2.6.24 are available. For older kernels, you can grab a git commit fixing it, or check the diff between the 2.6.24.1 and 2.6.24.2 patch (I think the latter looks nicer :-P).

Start them compilers!