user1878: In this thread, Luke Jr mentioned Collective Transactions would be a way for clients to increase anonymity when issuing transactions.

How would such an implementation work?

(Please provide technical details or references as available)

user13925: Dark Wallet is probably the closest to actively implementing something along these lines in a client.
See:
https://wiki.unsystem.net/index.php/DarkWallet/Alpha#Mixing

When sending, the transaction is sent to an internal mixer, that
  starts announcing on the coinjoin channel, if another peer answers,
  both will negotiate a shared transaction that includes both peers
  inputs and outputs. If successful the final transaction will be sent
  into the network.
You can see how a transaction from the mixer looks
  https://blockchain.info/tx/c38aac9910f327700e0f199972eed8ea7c6b1920e965f9cb48a92973e7325046

And also the multisig section that follows:

Multisig funds are special bitcoin addresses that can be spent from
  only by a number of participants signing the transactions. This means
  accounts can be held among several people or devices, and several
  signatures (above some threshold) will be needed to spend.


1878: <p><a href="https://bitcointalk.org/index.php?topic=24784.msg1308187#msg1308187" rel="nofollow">In this thread, Luke Jr mentioned Collective Transactions</a> would be a way for clients to increase anonymity when issuing transactions.</p>

<ul>
<li>How would such an implementation work?</li>
</ul>

<p>(Please provide technical details or references as available)</p>
 13925: <p>Dark Wallet is probably the closest to actively implementing something along these lines in a client.</p>

<p>See:</p>

<p><a href="https://wiki.unsystem.net/index.php/DarkWallet/Alpha#Mixing" rel="nofollow">https://wiki.unsystem.net/index.php/DarkWallet/Alpha#Mixing</a></p>

<blockquote>
  <p>When sending, the transaction is sent to an internal mixer, that
  starts announcing on the coinjoin channel, if another peer answers,
  both will negotiate a shared transaction that includes both peers
  inputs and outputs. If successful the final transaction will be sent
  into the network.</p>
  
  <p>You can see how a transaction from the mixer looks
  <a href="https://blockchain.info/tx/c38aac9910f327700e0f199972eed8ea7c6b1920e965f9cb48a92973e7325046" rel="nofollow">https://blockchain.info/tx/c38aac9910f327700e0f199972eed8ea7c6b1920e965f9cb48a92973e7325046</a></p>
</blockquote>

<p>And also the multisig section that follows:</p>

<blockquote>
  <p>Multisig funds are special bitcoin addresses that can be spent from
  only by a number of participants signing the transactions. This means
  accounts can be held among several people or devices, and several
  signatures (above some threshold) will be needed to spend.</p>
</blockquote>
