Although looking at BTCGuild's block find history it doesn't look like it has found blocks in every hour that we've seen the 10 BTC deposits occur. Some hours more than 1 block is found, but in some of the hours no blocks were found (but the 10 BTC still transferred).
I've never used BTCGuild before though; can anyone familiar with their payout options explain what might be occurring?
You can set the payout to a certain amount for a certain time interval.
In this case it is set to 10 BTC paid every hour, as long as the balance is big enough.
If I am understanding correctly here, AM is then hashing away on BTCGuild under another alias in addition to the old account? And that would explain the 10BTC withdrawals out of there?