TWIRL: Are 1024-bit RSA Keys Unsafe?

This came across the Interesting-People list today: a preliminary draft of a paper, co-authored by Adi Shamir, that proposes new hardware for factoring large numbers. It is claimed that a machine could be built which would be "3-4 orders of magnitude more cost effective than the best previously published designs," and that "the NFS sieving step for 1024-bit RSA keys can be completed in less than a year by a $10M device." For background, here's a primer on key length in symmetric and asymmetric crypto.