As someone who watched the proceedings I can confirm that the only dead things were our interest in using Ruby 1.8 and a rather large slab of smoked meat.
Not just "something", but something that has "died" or ceases to exist in its prior form and the "postmortem" is generally the detailed analysis of what happened.
The second definition given does not refer to "death" at all and is commonly used in science and business contexts. It usually refers to the project (or the "event") being over at the point of discussion.