I think someone may be withholding blocks on BTC Guild.

Someone (BTC talk user Brucexie claimed to be shorted 200+ BTC from eligius and it appears they were selfish mining see the below thread
https://bitcointalk.org/index.php?topic=650831.0

They claim that 17JkL94B2ngJg4QQZuiozDQjnxXB6B7yTc and 1Gu8zxRi8cyENV8CQe52D7QEsiZ7ruT73u belong to the selfish miners.

Looking at these addresses on blockchain.info, it looks like that both addresses are receiving payouts from BTC Guild.

Checking the PPLNS stats page on BTC Guild I see that they had had very bad luck 67% over 3 days and 83% over one week.

Based on this I would think that it is likely that "Brucexie" or the person/people who control the above addresses are selfish mining at BTC Guild.

It looks like they have set the automatic payout to receive payouts in 10 BTC intervals

If someone who has access to the "back office" stats at BTC Guild could please look into any users who have the payout address set to the above addresses and/or any accounts/ipaddresses that are showing very bad luck?

I would recommend disabling payout instead of disconnecting them, as they would be less likely to notice this right away and would slow down their effort to selfish mine on large pools.

EDIT: changed selfish mining --> block withholding to use proper terminology