I think the MSDN article can give you more information.
From what I read is that a Dependency Property relies on other values.
The purpose of dependency properties
is to provide a way to compute the
value of a property based on the value
of other inputs. These other inputs
might include system properties such
as themes and user preference,
just-in-time property determination
mechanisms such as data binding and
animations/storyboards, multiple-use
templates such as resources and
styles, or values known through
parent-child relationships with other
elements in the element tree. In
addition, a dependency property can be
implemented to provide self-contained
validation, default values, callbacks
that monitor changes to other
properties, and a system that can
coerce property values based on
potentially runtime information.
Derived classes can also change some
specific characteristics of an
existing property by overriding
dependency property metadata, rather
than overriding the actual
implementation of existing properties
or creating new properties.
