Mark Pilgrim: "I take in a lot of raw data, synthesize it, and spit it back out in ways that many people can understand."
Mark Pilgrim and Neil Deakin are two very smart web developers, but more importantly they both have the ability to document complex web technology in laymans language - so that wannabes can learn it too.
This is different to technical writing, which means documenting a piece of software for its end users.
One of the best ways to learn something is to document it. The beauty of the read/write web is that it makes it easy to do this, and easy for everyone to contribute.
Revision 24/7/03: I struck out the sentence about technical writing, because tech writing as a discipline actually covers writing for both wannabes and end users - and many other types of audiences too.