KentBeck was kind enough to share some of his day (30-dec-1999) with me
at his new office in Merlin. His (huge) dog Zoomer didn't even bite me.
Here is the crux of the interview.
-ChrisTilt
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ProgramManager

Chris:
It seems there is a role missing, that of the Program Manager. In
a project that spans many of the functional disciplines within a
company, the ProgramManager often coordinates and is "responsible"
for the project to executive management. How is this done in XP?

Kent:
Yes, this role exists, but we have to be careful not to think
this person has control of the project. Decisions are pushed down to the
team. The program manager coordinates the commitment schedule with
external dependencies. This role applies mainly to non-fixed price
projects.
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ProductDesigner

Chris:
We had some trouble understanding the "customer" role when
applying XP to our business model. We have hundreds of customers
and thus look more like a shrink-wrap business. We plan to put a
product designer in the role of customer to represent the many needs
and to make sure the stories form a coherent architecture. Does this sound
right?

Kent:
Yes. This is another example of the difference between shrink-wrap
and fixed-price projects. However, many companies hire an expert
from their target market to play the role of customer. It's a question
of which risk you want to take. A product designer that has to learn
the problem domain, or an expert in the domain that has to learn
design?
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Specialists/Experts

Chris:
With regard to code ownership, we have some deep technical areas that
we tend to produce specialists from. XP says this is bad, but having
specialists is a powerful information resouce. For example, when I
am not in the office, no one can answer questions about product S.

Kent:
Sooo, experts are bad, right?

Chris:
Yeh, ok. Should we capture the knowledge on intranet web pages?

Kent:
Put the knowledge into the code. By using good variable names
and comments, you can express a lot of information in the code.
Put it into tests. The system's behaviour is expressed by the
tests, so you can write tests just for documentation. If the system
is based on something that has a quirk and you learn it, put a test
in that communicates the quirk; the test case will make sure the
quirk is still there.

Chris:
This sounds like a set of assertions about the system. Is that right?

Kent:
Yes.
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Architecture (The guru approach)

Chris:
As with most interesting problems, the underlying model is hard.
If we are to distribute all aspects of the project, how do we arrive at
a strong model of the problem?

Kent:
Not all phases of the project are distributed. The distribution of
effort in XP is about getting the most out of ourselves by concurrent
execution on the most important parts of a system first. Determination
of which business problems to attack in the market is a different kind
of activity in which a smaller group of people (maybe one or two) focus.
This is usually done by the customer (marketing on a shrink-wrap
product). Likewise, the underlying model of a product might be
developed by a few people. This should result in a metaphor that guides
the whole project.
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CategoryInterview