He is not only one of the smartest guys I ever met, he's also one of the nicest.
I was lucky enough to be working at Digital in the late 80s when we started hiring the big brains in transaction processing -- including Jim -- to help us compete against IBM. Never mind that we should probably have been focused on personal computers, instead. For someone whose first job was converting batch applications into online TP applications, and who loves TP as much I do, it was a great time.
He visited Digital's TP heaquarters in Littleton, MA (where I worked) often and his presence was always felt throughout the building.
Although it might have been easy for him to consider our effort to be in competition with his book, he actually gave us the most thorough review or the manuscript and some very helpful comments, and agreed to write the foreword.
The tremendous industry reaction, as seen in the many articles and blog entries, is completely understandable. Jim invented, or helped invent, many technologies fundamental to the way the world works every day, including the relational database, high availablilty and fault tolerance mechansims, scalability algorithms, transaction processing mechanisms, and many many others. Yet you would never hear him boast about it. He always preferred to think of himself as part of the team.
When he won the Turing prize I sent him a congratulatory email and received back a characteristically very nice and humble message.
I cannot be too sad, because he is still just missing, but that news was a great shock, and the fact that it has been almost a week now is not good.