  We study a dense colloidal suspension confined between two quasiparallel
glass plates as a model system for a supercooled liquid in confined geometries.
We directly observe the three-dimensional Brownian motion of the colloidal
particles using laser scanning confocal microscopy. The particles form dense
layers along the walls, but crystallization is avoided as we use a mixture of
two particle sizes. A normally liquid-like sample, when confined, exhibits
slower diffusive motion. Particle rearrangements are spatially heterogeneous,
and the shapes of the rearranging regions are strongly influenced by the
layering. These rearranging regions become more planar upon confinement. The
wall-induced layers and changing character of the spatially heterogeneous
dynamics appear strongly connected to the confinement induced glassiness.
