What exactly is the problem you are hinting? I don't see it.
The article discusses how to deanonymize bitcoin transactions that make use of CoinJoin (which is a simple way of mixing a small number of transactions together in a block). DarkCoin's "darksend" is based on coinjoin, so I presume that it is equally unsafe (but perhaps there are some extra subtleties). The point is: If anoncoin gets zerocoin working, it will be the only truly anonymous coin out there...
I quote from the article:
Bitcoin users in need of serious transaction privacy should avoid popular services like Blockchains SharedCoin and other CoinJoin implementations, according to a well-known security expert.
Consultant Kristov Atlas, author of the book Anonymous Bitcoin, published a security advisory today saying weaknesses in SharedCoin offered privacy only from unskilled examiners of the bitcoin blockchain and even then, only until more sophisticated analysis tools were made user-friendly enough for the average user to deploy.