[nfmangano]

There was a presentation that tackled this question at the most recent ICSE conference. Here's the paper: "UML in practice", http://oro.open.ac.uk/35805/8/UML%20in%20practice%208.pdf

The author interviewed people from 50 different major companies, and found people's use fit within the following:

Category of UML Use, Instances of Declared Current Use

no UML, 35

retrofit, 1

automated code generation, 3

selective, 11

wholehearted, 0

From the conclusion: "The majority of those interviewed simply do not use UML, and those who do use it tend to do so selectively and often informally."

In my own experience and research, people draw extensively, but have their own shorthand for writing things specific to their domain.