  In this paper, as a generalization of Kirillov's orbit theory, we explore the
relationship between the dressing orbits and irreducible *-representations of
the Hopf C*-algebras (A,\Delta) and (\tilde{A}, \tilde{\Delta}) we constructed
earlier. We discuss the one-to-one correspondence between them, including their
topological aspects.
  On each dressing orbit (which are symplectic leaves of the underlying Poisson
structure), one can define a Moyal-type deformed product at the function level.
The deformation is more or less modeled by the irreducible representation
corresponding to the orbit. We point out that the problem of finding a direct
integral decomposition of the regular representation into irreducibles
(Plancherel theorem) has an interesting interpretation in terms of these
deformed products.
