Back in March of 2011, I won an artist's Kiriban contest. Initial messages with details and references were sent, and everything seemed fine. Two months later, I contacted the artist and asked about the pic. The reply stated that the artist was looking into new ways to color their art and that they'd work on the pic when motivation struck them.
That was the last I heard from them. Since May, I have sent a polite request for a status every 1-2 months, the last time being in January. No reply. I know the artist hasn't disappeared, because he has posted nearly 50 submissions in that time, and according to FA, he has read all 4 of my unanswered messages.
Now, I can understand long wait times (especially for free art). Hell, if he were actually responding to my messages I'd pretty much have no problem. But being ignored like this just strikes me as very bad form.