Alan McKinnon <alan.mckinnon@gmail.com> at Thursday 26 June 2008, 10:54:43
> The calculation is quite simple - measure how quickly a specific
> computer can match keys. Divide this into the size of the keyspace. The
> average time to brute force a key is half that value. AFAIK this still
> averages out at enormous numbers of years, even at insane calculation
> rates like what RoadRunner can achieve.

According to Wikipedia RoadRunner is designed for 1.7 petaflops in peak.  
Assuming for the sake of simplicity, that decryption can be performed 
within a single flop:

(2^256) / (1.7 * 10^15) / 2 ~= 3.5 * 10^61

In years: 

3.5 * 10^61 / 3600 / 24 / 356 ~= 10^54

Correct me if I'm wrong, but it seems impossible to me, to reduce this get 
the required amount somewhere near to the life time of a human being ;)

-- 
Freedom is always the freedom of dissenters.
                                      (Rosa Luxemburg)