user78: From the forum:

Eligius already will accept any transaction, "standard" or not,
without bias.
...
Indeed, and Eligius' willingness to do so indirectly cost MTGOX many
thousands of bitcoins when a software bug caused them to send some
weird transactions that Eligius mined.

Can anyone provide a reference that explain this incident? When did it occur?

user108: It refers to an occurrence in October 2011 when someone sent a lot of bitcoins to an incorrect public address: someone fucked up and lost ALOT of money . Casascius stated that he thinks it was done by Luke-Jr's Eligius mining pool: Re: someone fucked up and lost ALOT of money

The way I understand it, these transactions were nonstandard enough
  that normal miners and clients would already refuse to relay or
  process them (but will accept them in a mined block). And that the
  only way these got into a block was that he teamed up with Luke-Jr's
  Eligius mining pool which has been modified to explicitly allow these
  nonstandard transactions for a fee (or other negotiated arrangement).

Earlier from the same thread, Re: someone fucked up and lost ALOT of money: 

Maybe this helps. It seems MtGox made a mistake somewhere.

MagicalTux: that's a problem, but not the worst problem we ever faced
MagicalTux: all the broken withdraws have been re-issued
MagicalTux: just spent one week of BTC-only income



78: <p><a href="https://bitcointalk.org/index.php?topic=58579.msg690179#msg690179" rel="nofollow noreferrer">From the forum</a>:</p>
<blockquote>
<p>Eligius already will accept any transaction, &quot;standard&quot; or not,
without bias.</p>
<p>...</p>
<p>Indeed, and Eligius' willingness to do so indirectly cost MTGOX many
thousands of bitcoins when a software bug caused them to send some
weird transactions that Eligius mined.</p>
</blockquote>
<p>Can anyone provide a reference that explain this incident? When did it occur?</p>
 108: <p>It refers to an occurrence in October 2011 when someone sent a lot of bitcoins to an incorrect public address: <a href="https://bitcointalk.org/index.php?topic=50206" rel="nofollow">someone fucked up and lost ALOT of money</a> . Casascius stated that he thinks it was done by Luke-Jr's Eligius mining pool: <a href="https://bitcointalk.org/index.php?topic=50206.msg598836#msg598836" rel="nofollow">Re: someone fucked up and lost ALOT of money</a></p>

<blockquote>
  <p>The way I understand it, these transactions were nonstandard enough
  that normal miners and clients would already refuse to relay or
  process them (but will accept them in a mined block). And that the
  only way these got into a block was that he teamed up with Luke-Jr's
  Eligius mining pool which has been modified to explicitly allow these
  nonstandard transactions for a fee (or other negotiated arrangement).</p>
</blockquote>

<p>Earlier from the same thread, <a href="https://bitcointalk.org/index.php?topic=50206.msg598227#msg598227" rel="nofollow">Re: someone fucked up and lost ALOT of money</a>: </p>

<blockquote>
  <p>Maybe this helps. It seems MtGox made a mistake somewhere.</p>
  
  <blockquote>
    <p>MagicalTux: that's a problem, but not the worst problem we ever faced</p>
    
    <p>MagicalTux: all the broken withdraws have been re-issued</p>
    
    <p>MagicalTux: just spent one week of BTC-only income</p>
  </blockquote>
</blockquote>
