Cassiopeia A is one of the most studied astronomical objects and yet there are still
new and exciting things to learn about this supernova remnant.  I will concentrate on
three recent X-ray and infrared results.  First, while Cas A is no longer the
youngest supernova remnant in our galaxy, we do finally know what type of explosion
it was - a type  IIb - based on the infrared light echoes initially discovered with
Spitzer.  Second, from 8 years of Chandra observations we can now track the X-ray
evolution of Cas A on small spatial scales.  The velocity of the blast wave is moving
a bit slower than what is expected based on hydrodynamic modelling.  One plausible
explanation is that the "missing" energy went into particle acceleration.  Finally,
the 3-dimensional reconstruction of Cas A using Spitzer and Chandra data shows that
the ejecta have a flattened distribution despite the roundness of the blast wave. 
The well-known jets in Cas A and the Fe ejecta protrusions seen to the north and
southeast are all in the same flattened plane.  These are all exciting puzzle pieces
that supernova modelers can use to determine how stars blow up.