Technology Review has some of the initial attempts to knock off Aubrey de Grey's thesis on the feasibility of immortality (actually, indefinite lifespace is a better phrase). I haven't read them yet, but my readers may be interested. They also contain a response to each by de Grey, and a counterresponse.

[Via the newly redesigned Cosmic Log website, which now looks a lot more bloggy, though I suspect that Alan still goes through an editor, or at least an uploader...]