I don't have any good stories to tell about him; we moved in similar SF circles but had different friends, I've probably spoken to him a dozen or so times over the years. I did once point out a science gaffe in Surface Detail, but that's about it. Nevertheless he was one of my favourite authors, and he'll be badly missed by everyone who knew him or liked his work.
http://www.bbc.co.uk/news/uk-22835047