QUESTION: 
What will Hubble's role be in the Pluto Express flyby mission?

ANSWER: 
Excellent question.  I'm going to break this question into two
parts.  One is the role of Hubble's Space Telescope Science Institute
and the other is the role of the Hubble Space Telescope itself.

I cannot speak authoritatively on the plans and activities of the
Institute or the many people associated with it.  I can speculate
that there will be some people here who are following the progress
of the Pluto Express and some may get involved in various aspects
of it.  Some will no doubt be interested in the organizational
aspects of the mission, others in the engineering and technical
aspects, and many in the scientific planning and particularly the
results of the flyby.  I have not heard that the Institute will
be directly involved with that mission though.  You might be
able to follow individual's involvement in it by searching the
World Wide Web and contacting some of them directly.

However, I suspect the more interesting part of the question is
how the Hubble Space Telescope itself can contribute to the Pluto
mission.  As HST observes Pluto in the months and years leading
up to the actual flyby, it will provide the astronomical community
with precise positions of Pluto (and its moon Charon) which the mission
planners will almost undoubtedly use to refine their trajectory and
timing of the visit.  For example they should be able to know more
precisely where its moon will be at any given time so they don't
accidentally run into it and will perhaps allow measurements of it
as well.  Additionally, the observations of the changing surface features
on Pluto will allow them to perhaps target regions of particular 
interest.

If a bright spot, say, suddenly appears or fades, the mission planners
might adjust their pointing or instruments to take advantage of
the event.

At the time of the flyby, if HST is still flying, I'd bet that we
will be asked to make coordinated observations to compare results.
As proposals to use HST are accepted for use no more than about 18 months
in the future, I don't believe there are any currently active observing
programs for this specific purpose, but it's almost certain there will
be by the time the Express reaches Pluto.

As far as I know, there is no direct coordination between the Space 
Telescope Science Institute and the Pluto Express project for mission 
planning, but the Pluto planners will certainly know of HST's 
capabilities and will look for any information that can help them.  We 
will be glad to provide it.
 
Continue to monitor the progress of the Pluto mission and perhaps
over the years you can watch as an observation from HST gets picked
up for use, both during approach and during the flyby itself.
William Hathaway