Well, we had another nappy-free afternoon in the garden and ds used the potty several times for wees (with much encouragement and reminding) . He had several friends round, some of whom are potty trained so they were virtually queueing for the potty, and one of them did a tiny bit of poo. I don't know if it was ds or one of the others, but I popped him in a nappy later on and he produced a poo shortly afterwards so I think it may have been him and he may have been trying to hold it in until he had a nappy on. I've tried encouraging him with the promise of chocolate buttons and also tried elliot's idea of popping him on the potty after meals but no luck yet.
Fruitloop, it sounds to me like your ds does have bladder control. How about trying bribery? Have you been getting him to sit on the potty at all before this? ds has been sitting on it before and after his bath for months now, and he has often produced a wee. Maybe your ds just needs some time to get used to the idea.