this is pretty important stuff though, if all these accounts are truly dead, then the threat of a complete bitcoin wipeout (down to $10 or less) is far less than I initially calculated, as these coins can't come back into the market as sell orders en masse.
The dead wallets contains near 2,5M of bitcoins (actually we can estimate a 22% of all the bitcoins with the great majority are from addresses with 25-50BTC) : there is a post on the italian section of the forum in which all the movements of all the wallets since 2009, we have considered that the wallets with no input or out for more than 2 years are to be considered dead
https://bitcointalk.org/index.php?topic=353156.120