The moderators have pointed this out to me now that this is a hot topic for discussion at times and people feel unsafe at the apparent lack of a tumbler in the Silk Road market. I would like to correct this misunderstanding as Silk Road does actually have a mixing system in place and has done since the start.
We are currently using the same system that the former Silk Road market used, which is to use deposits as a funding pool and by having thousands of addresses with a low volume of bitcoin in them enter the general pool of addresses. Once a withdrawal is made, a random selection of addresses is chosen by the system and is used to fund the withdrawal for a vendor with the rest entering individual change addresses.
As I said initially, this is the same system that the old market used and generally many users felt this was sufficient protection as it fulfills the objective of not making it possible for the buyer to identify the vendors bitcoin address through following the blockchain alone, although as yet both systems are not perfect as it still allows an adversary to identify what is a deposit and what is a withdrawal if they can make enough deposits to at least have a small amount of their initial bitcoin in most withdrawals (requires at least $2,000,000 in bitcoin at this moment in time).
Our current work long term is geared towards a better solution than this which should make the identification of withdrawals and deposits far harder. The exact plans of this proposed solution I do not wish to discuss publicly, but I hope this post has cleared up the confusion surrounding the matter and remember to always use at least 1 other method of mixing your coins.
