The malleability issue seems real enough.  Something was published on it on 21 january on bitcoin.it, maybe someone had to try it out...

That said I did a withdrawal on 28th january from Mt. Gox (and it was taken from my balance on 28th january). It failed to get in to the receiver until 31st january after I had complained about it with their support. Blockchain.info did not show any transaction coming in to the receiver address on the 28th of january with the original txout or with anything different. The support ticket went unanswered until after the transaction was finally done (on the 31st of january). The answer when it did come on the 5th of february claimed that some users were experiencing delays in withdrawals and that I had to rest assured that this was only affecting limited users and transactions.....

I was immediately distrustful of this statement, and this weekends saga much confirms it.