I have the same question. Mt Gox requires a verified account
In order to be upgraded to a verified account, we need a proof of residence document. This is usually either a Utility Bill, a Tax Return, or a Voter's Registration Form. Please scan a copy of your ID and upload it on this page. Note that:
The card must be clear and legible.
It cannot be an unopened envelope.
It cannot be a bank statement.
It cannot be edited or censored in any way.
It must be either in JPEG (.jpg), PNG (.png) or PDF (.pdf) format.
It must have been issued within the last 3 months.
I don't know if I feel too good about this. I'm not tinfoil hat paranoid, but don't really like putting info like that on there.
Or is this paranoia not required and do they keep your info safe?