So, seems the signal thread performance of A57 core will be close to that of Intel Yonah core (Core microarchitecture), and a bit lower than that of Merom core (Core 2 microarchitecture), if SpecInt2000 can be taken linearly, which was designed to.
SpecInt2000 scores (http://www.spec.org/cpu2000/results/cint2000.html):
Core Duo T2600@2.17G = 1796
Core 2 Duo T7400@2.17G = 2284
They were released in 2006 (Jan and Aug?), and TDPs are 31W and 34W respectively.